diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7a8d6b6..65ed0a9 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,7 +1,45 @@
 cmake_minimum_required(VERSION 3.10.0)
 project(BetterSTL VERSION 0.1.0 LANGUAGES C CXX)
+set(CMAKE_EXPORT_COMPILE_COMMANDS ON)
 
-add_library(BetterSTL src/BigInteger.cpp
+# 定义源文件
+set(BETTERSTL_SOURCES 
+    src/BigInteger.cpp
     src/BigDecimal.cpp)
 
-include_directories(include)
+# 生成静态库 (.a 文件)
+add_library(BetterSTL_static STATIC ${BETTERSTL_SOURCES})
+target_include_directories(BetterSTL_static PUBLIC include)
+set_target_properties(BetterSTL_static PROPERTIES 
+    OUTPUT_NAME BetterSTL
+    PREFIX lib)
+
+# 生成动态库 (.so 文件)
+add_library(BetterSTL_shared SHARED ${BETTERSTL_SOURCES})
+target_include_directories(BetterSTL_shared PUBLIC include)
+set_target_properties(BetterSTL_shared PROPERTIES 
+    OUTPUT_NAME BetterSTL
+    PREFIX lib)
+
+# 默认链接到静态库
+add_library(BetterSTL ALIAS BetterSTL_static)
+
+enable_testing()
+
+add_executable(BigIntegerTests tests/BigIntegerTest.cpp)
+target_include_directories(BigIntegerTests PRIVATE include)
+target_link_libraries(BigIntegerTests PRIVATE BetterSTL_static)
+add_test(NAME BigIntegerTests COMMAND BigIntegerTests)
+
+add_executable(BigDecimalTests tests/BigDecimalTest.cpp)
+target_include_directories(BigDecimalTests PRIVATE include)
+target_link_libraries(BigDecimalTests PRIVATE BetterSTL_static)
+add_test(NAME BigDecimalTests COMMAND BigDecimalTests)
+
+# 生成导出信息用于外部使用
+install(TARGETS BetterSTL_static BetterSTL_shared
+        LIBRARY DESTINATION lib
+        ARCHIVE DESTINATION lib
+        RUNTIME DESTINATION bin)
+install(DIRECTORY include/ DESTINATION include)
+
diff --git a/include/BigDecimal.hpp b/include/BigDecimal.hpp
new file mode 100644
index 0000000..322cc73
--- /dev/null
+++ b/include/BigDecimal.hpp
@@ -0,0 +1,72 @@
+#pragma once
+
+#include <string>
+#include "BigInteger.hpp"
+
+namespace bstl {
+
+class BigDecimal {
+public:
+    BigDecimal();
+    BigDecimal(int value);
+    BigDecimal(long long value);
+    BigDecimal(double value);
+    explicit BigDecimal(const std::string& value);
+    explicit BigDecimal(const char* value);
+    BigDecimal(const BigInteger& unscaledValue, int scale);
+    BigDecimal(const BigDecimal& other) = default;
+    BigDecimal& operator=(const BigDecimal& other) = default;
+
+    bool isZero() const;
+    int sign() const;
+    int getScale() const;
+    BigInteger getUnscaledValue() const;
+    std::string toString() const;
+
+    // Comparison operators
+    bool operator==(const BigDecimal& other) const;
+    bool operator!=(const BigDecimal& other) const;
+    bool operator<(const BigDecimal& other) const;
+    bool operator>(const BigDecimal& other) const;
+    bool operator<=(const BigDecimal& other) const;
+    bool operator>=(const BigDecimal& other) const;
+
+    bool operator==(int value) const;
+    bool operator!=(int value) const;
+    bool operator<(int value) const;
+    bool operator>(int value) const;
+    bool operator<=(int value) const;
+    bool operator>=(int value) const;
+
+    bool operator==(double value) const;
+    bool operator!=(double value) const;
+    bool operator<(double value) const;
+    bool operator>(double value) const;
+    bool operator<=(double value) const;
+    bool operator>=(double value) const;
+
+    // Arithmetic operators
+    BigDecimal operator+() const;
+    BigDecimal operator-() const;
+    BigDecimal& operator+=(const BigDecimal& other);
+    BigDecimal& operator-=(const BigDecimal& other);
+    BigDecimal& operator*=(const BigDecimal& other);
+    BigDecimal& operator/=(const BigDecimal& other);
+
+    BigDecimal operator+(const BigDecimal& other) const;
+    BigDecimal operator-(const BigDecimal& other) const;
+    BigDecimal operator*(const BigDecimal& other) const;
+    BigDecimal operator/(const BigDecimal& other) const;
+
+    BigDecimal abs() const;
+    BigDecimal round(int scale) const;
+
+private:
+    BigInteger unscaledValue_;  // 去掉小数点后的值
+    int scale_;                 // 小数点后的位数
+
+    static void alignScale(BigInteger& lhs, int& lhsScale,
+                          BigInteger& rhs, int& rhsScale);
+};
+
+} // namespace bstl
diff --git a/include/BigInteger.hpp b/include/BigInteger.hpp
new file mode 100644
index 0000000..ed6a4a9
--- /dev/null
+++ b/include/BigInteger.hpp
@@ -0,0 +1,69 @@
+#pragma once
+
+#include <string>
+
+namespace bstl {
+
+class BigInteger {
+public:
+    BigInteger();
+    BigInteger(int value);
+    BigInteger(long long value);
+    BigInteger(unsigned long long value);
+    explicit BigInteger(const std::string& value);
+    explicit BigInteger(const char* value);
+    BigInteger(const BigInteger& other) = default;
+    BigInteger& operator=(const BigInteger& other) = default;
+
+    bool isZero() const;
+    int sign() const;
+    std::string toString() const;
+
+    bool operator==(const BigInteger& other) const;
+    bool operator!=(const BigInteger& other) const;
+    bool operator<(const BigInteger& other) const;
+    bool operator>(const BigInteger& other) const;
+    bool operator<=(const BigInteger& other) const;
+    bool operator>=(const BigInteger& other) const;
+
+    bool operator==(int value) const;
+    bool operator!=(int value) const;
+    bool operator<(int value) const;
+    bool operator>(int value) const;
+    bool operator<=(int value) const;
+    bool operator>=(int value) const;
+
+    bool operator==(long long value) const;
+    bool operator!=(long long value) const;
+    bool operator<(long long value) const;
+    bool operator>(long long value) const;
+    bool operator<=(long long value) const;
+    bool operator>=(long long value) const;
+
+    BigInteger operator+() const;
+    BigInteger operator-() const;
+    BigInteger& operator+=(const BigInteger& other);
+    BigInteger& operator-=(const BigInteger& other);
+    BigInteger& operator*=(const BigInteger& other);
+    BigInteger& operator/=(const BigInteger& other);
+
+    BigInteger operator+(const BigInteger& other) const;
+    BigInteger operator-(const BigInteger& other) const;
+    BigInteger operator*(const BigInteger& other) const;
+    BigInteger operator/(const BigInteger& other) const;
+
+private:
+    std::string digits_;  // 无符号数字，从高位到低位
+    int sign_;            // -1, 0, 1
+
+    static std::string trimLeadingZeros(const std::string& value);
+    static int compareAbs(const std::string& a, const std::string& b);
+    static std::string addAbs(const std::string& a, const std::string& b);
+    static std::string subAbs(const std::string& a, const std::string& b);
+    static std::string mulAbs(const std::string& a, const std::string& b);
+    static std::string divAbs(const std::string& a, const std::string& b);
+};
+
+using BitInteger = BigInteger;
+
+} // namespace bstl
diff --git a/include/bstl/bstl.hpp b/include/bstl/bstl.hpp
index efaeebf..91fc56c 100644
--- a/include/bstl/bstl.hpp
+++ b/include/bstl/bstl.hpp
@@ -1,6 +1,7 @@
+
 #ifndef BETTERSTL_BSTL_HPP
-#define BETTERSTL_BSTL_HPP
-
+#include<bstl/BigDecimal.hpp>
+#include<bstlBigInteger.hpp>
 #include <bstl/bstlint.hpp>
-
+#define BETTERSTL_BSTL_HPP
 #endif //BETTERSTL_BSTL_HPP
diff --git a/src/BigDecimal.cpp b/src/BigDecimal.cpp
index 840565c..a09b0e5 100644
--- a/src/BigDecimal.cpp
+++ b/src/BigDecimal.cpp
@@ -1 +1,341 @@
-#include <bstl/bitdecimal.hpp>
\ No newline at end of file
+#include "BigDecimal.hpp"
+
+#include <stdexcept>
+#include <sstream>
+#include <cmath>
+
+namespace bstl {
+
+BigDecimal::BigDecimal() : unscaledValue_(0), scale_(0) {}
+
+BigDecimal::BigDecimal(int value) : unscaledValue_(value), scale_(0) {}
+
+BigDecimal::BigDecimal(long long value) : unscaledValue_(value), scale_(0) {}
+
+BigDecimal::BigDecimal(double value) : scale_(0) {
+    if (value == 0.0) {
+        unscaledValue_ = 0;
+        scale_ = 0;
+        return;
+    }
+
+    // 将浮点数转换为字符串，然后解析
+    std::ostringstream oss;
+    oss.precision(15);
+    oss << value;
+    *this = BigDecimal(oss.str());
+}
+
+BigDecimal::BigDecimal(const std::string& value) : unscaledValue_(0), scale_(0) {
+    if (value.empty()) {
+        return;
+    }
+
+    std::string text = value;
+
+    // 去掉前后空格
+    size_t start = 0, end = text.size();
+    while (start < end && text[start] == ' ') start++;
+    while (end > start && text[end - 1] == ' ') end--;
+    text = text.substr(start, end - start);
+
+    if (text.empty()) {
+        return;
+    }
+
+    // 查找小数点位置
+    size_t dotPos = text.find('.');
+    if (dotPos != std::string::npos) {
+        scale_ = text.size() - dotPos - 1;
+        std::string digits = text.substr(0, dotPos) + text.substr(dotPos + 1);
+        unscaledValue_ = BigInteger(digits);
+    } else {
+        scale_ = 0;
+        unscaledValue_ = BigInteger(text);
+    }
+}
+
+BigDecimal::BigDecimal(const char* value)
+    : BigDecimal(value == nullptr ? std::string("0") : std::string(value)) {}
+
+BigDecimal::BigDecimal(const BigInteger& unscaledValue, int scale)
+    : unscaledValue_(unscaledValue), scale_(scale) {
+    if (scale < 0) {
+        throw std::invalid_argument("scale cannot be negative");
+    }
+}
+
+bool BigDecimal::isZero() const {
+    return unscaledValue_.isZero();
+}
+
+int BigDecimal::sign() const {
+    return unscaledValue_.sign();
+}
+
+int BigDecimal::getScale() const {
+    return scale_;
+}
+
+BigInteger BigDecimal::getUnscaledValue() const {
+    return unscaledValue_;
+}
+
+std::string BigDecimal::toString() const {
+    if (isZero()) {
+        return "0";
+    }
+
+    std::string digitStr = unscaledValue_.toString();
+
+    // 处理符号
+    bool negative = false;
+    if (digitStr[0] == '-') {
+        negative = true;
+        digitStr = digitStr.substr(1);
+    }
+
+    // 插入小数点
+    if (scale_ == 0) {
+        return (negative ? "-" : "") + digitStr;
+    }
+
+    if (static_cast<int>(digitStr.size()) <= scale_) {
+        // 需要前置 "0."
+        std::string result = "0.";
+        for (int i = 0; i < scale_ - static_cast<int>(digitStr.size()); i++) {
+            result += "0";
+        }
+        result += digitStr;
+        return (negative ? "-" : "") + result;
+    }
+
+    int dotPos = digitStr.size() - scale_;
+    std::string result = digitStr.substr(0, dotPos) + "." + digitStr.substr(dotPos);
+    return (negative ? "-" : "") + result;
+}
+
+void BigDecimal::alignScale(BigInteger& lhs, int& lhsScale,
+                            BigInteger& rhs, int& rhsScale) {
+    if (lhsScale < rhsScale) {
+        // 左边需要扩大
+        for (int i = 0; i < rhsScale - lhsScale; i++) {
+            lhs = lhs * BigInteger(10);
+        }
+        lhsScale = rhsScale;
+    } else if (lhsScale > rhsScale) {
+        // 右边需要扩大
+        for (int i = 0; i < lhsScale - rhsScale; i++) {
+            rhs = rhs * BigInteger(10);
+        }
+        rhsScale = lhsScale;
+    }
+}
+
+bool BigDecimal::operator==(const BigDecimal& other) const {
+    if (isZero() && other.isZero()) return true;
+    BigInteger lhs = unscaledValue_;
+    BigInteger rhs = other.unscaledValue_;
+    int lhsScale = scale_;
+    int rhsScale = other.scale_;
+    alignScale(lhs, lhsScale, rhs, rhsScale);
+    return lhs == rhs;
+}
+
+bool BigDecimal::operator!=(const BigDecimal& other) const {
+    return !(*this == other);
+}
+
+bool BigDecimal::operator<(const BigDecimal& other) const {
+    if (unscaledValue_.sign() != other.unscaledValue_.sign()) {
+        return unscaledValue_.sign() < other.unscaledValue_.sign();
+    }
+
+    BigInteger lhs = unscaledValue_;
+    BigInteger rhs = other.unscaledValue_;
+    int lhsScale = scale_;
+    int rhsScale = other.scale_;
+    alignScale(lhs, lhsScale, rhs, rhsScale);
+
+    if (unscaledValue_.sign() >= 0) {
+        return lhs < rhs;
+    } else {
+        return lhs > rhs;
+    }
+}
+
+bool BigDecimal::operator>(const BigDecimal& other) const {
+    return other < *this;
+}
+
+bool BigDecimal::operator<=(const BigDecimal& other) const {
+    return *this < other || *this == other;
+}
+
+bool BigDecimal::operator>=(const BigDecimal& other) const {
+    return other <= *this;
+}
+
+bool BigDecimal::operator==(int value) const {
+    return *this == BigDecimal(value);
+}
+
+bool BigDecimal::operator!=(int value) const {
+    return !(*this == value);
+}
+
+bool BigDecimal::operator<(int value) const {
+    return *this < BigDecimal(value);
+}
+
+bool BigDecimal::operator>(int value) const {
+    return *this > BigDecimal(value);
+}
+
+bool BigDecimal::operator<=(int value) const {
+    return *this <= BigDecimal(value);
+}
+
+bool BigDecimal::operator>=(int value) const {
+    return *this >= BigDecimal(value);
+}
+
+bool BigDecimal::operator==(double value) const {
+    return *this == BigDecimal(value);
+}
+
+bool BigDecimal::operator!=(double value) const {
+    return !(*this == value);
+}
+
+bool BigDecimal::operator<(double value) const {
+    return *this < BigDecimal(value);
+}
+
+bool BigDecimal::operator>(double value) const {
+    return *this > BigDecimal(value);
+}
+
+bool BigDecimal::operator<=(double value) const {
+    return *this <= BigDecimal(value);
+}
+
+bool BigDecimal::operator>=(double value) const {
+    return *this >= BigDecimal(value);
+}
+
+BigDecimal BigDecimal::operator+() const {
+    return *this;
+}
+
+BigDecimal BigDecimal::operator-() const {
+    if (isZero()) {
+        return BigDecimal(0);
+    }
+    return BigDecimal(-unscaledValue_, scale_);
+}
+
+BigDecimal& BigDecimal::operator+=(const BigDecimal& other) {
+    *this = *this + other;
+    return *this;
+}
+
+BigDecimal& BigDecimal::operator-=(const BigDecimal& other) {
+    *this = *this - other;
+    return *this;
+}
+
+BigDecimal& BigDecimal::operator*=(const BigDecimal& other) {
+    *this = *this * other;
+    return *this;
+}
+
+BigDecimal& BigDecimal::operator/=(const BigDecimal& other) {
+    *this = *this / other;
+    return *this;
+}
+
+BigDecimal BigDecimal::operator+(const BigDecimal& other) const {
+    if (isZero()) return other;
+    if (other.isZero()) return *this;
+
+    BigInteger lhs = unscaledValue_;
+    BigInteger rhs = other.unscaledValue_;
+    int lhsScale = scale_;
+    int rhsScale = other.scale_;
+    alignScale(lhs, lhsScale, rhs, rhsScale);
+
+    return BigDecimal(lhs + rhs, lhsScale);
+}
+
+BigDecimal BigDecimal::operator-(const BigDecimal& other) const {
+    return *this + (-other);
+}
+
+BigDecimal BigDecimal::operator*(const BigDecimal& other) const {
+    if (isZero() || other.isZero()) {
+        return BigDecimal(0);
+    }
+
+    BigInteger result = unscaledValue_ * other.unscaledValue_;
+    int resultScale = scale_ + other.scale_;
+
+    return BigDecimal(result, resultScale);
+}
+
+BigDecimal BigDecimal::operator/(const BigDecimal& other) const {
+    if (other.isZero()) {
+        throw std::invalid_argument("division by zero");
+    }
+
+    if (isZero()) {
+        return BigDecimal(0);
+    }
+
+    // 先对齐 scale，然后做整数除法
+    BigInteger lhs = unscaledValue_;
+    BigInteger rhs = other.unscaledValue_;
+    int lhsScale = scale_;
+    int rhsScale = other.scale_;
+
+    // 使用更高的精度进行除法
+    // 乘以 10^precision 来获得更多的精度
+    int precision = 10;
+    for (int i = 0; i < precision; i++) {
+        lhs = lhs * BigInteger(10);
+    }
+
+    BigInteger quotient = lhs / rhs;
+    int resultScale = lhsScale - rhsScale + precision;
+
+    return BigDecimal(quotient, resultScale);
+}
+
+BigDecimal BigDecimal::abs() const {
+    if (unscaledValue_.sign() >= 0) {
+        return *this;
+    }
+    return BigDecimal(-unscaledValue_, scale_);
+}
+
+BigDecimal BigDecimal::round(int scale) const {
+    if (scale < 0) {
+        throw std::invalid_argument("scale cannot be negative");
+    }
+
+    if (scale >= scale_) {
+        return *this;
+    }
+
+    // 简单实现：直接截断到指定小数位数
+    int diff = scale_ - scale;
+    BigInteger divisor = BigInteger(10);
+    for (int i = 1; i < diff; i++) {
+        divisor = divisor * BigInteger(10);
+    }
+
+    BigInteger rounded = unscaledValue_ / divisor;
+    return BigDecimal(rounded, scale);
+}
+
+} // namespace bstl
diff --git a/src/BigInteger.cpp b/src/BigInteger.cpp
index 85f42c0..06ebca9 100644
--- a/src/BigInteger.cpp
+++ b/src/BigInteger.cpp
@@ -1 +1,378 @@
-#include <bstl/biginteger.hpp>
\ No newline at end of file
+#include "BigInteger.hpp"
+
+#include <algorithm>
+#include <stdexcept>
+#include <string>
+#include <vector>
+
+namespace bstl {
+
+std::string BigInteger::trimLeadingZeros(const std::string& value) {
+    size_t pos = 0;
+    while (pos < value.size() - 1 && value[pos] == '0') {
+        pos++;
+    }
+    return value.substr(pos);
+}
+
+int BigInteger::compareAbs(const std::string& a, const std::string& b) {
+    std::string ta = trimLeadingZeros(a);
+    std::string tb = trimLeadingZeros(b);
+    if (ta.size() != tb.size()) {
+        return ta.size() < tb.size() ? -1 : 1;
+    }
+    return ta.compare(tb) < 0 ? -1 : (ta.compare(tb) > 0 ? 1 : 0);
+}
+
+std::string BigInteger::addAbs(const std::string& a, const std::string& b) {
+    std::string result;
+    int carry = 0;
+    int i = static_cast<int>(a.size()) - 1;
+    int j = static_cast<int>(b.size()) - 1;
+    while (i >= 0 || j >= 0 || carry) {
+        int sum = carry;
+        if (i >= 0) sum += a[i--] - '0';
+        if (j >= 0) sum += b[j--] - '0';
+        result = char('0' + sum % 10) + result;
+        carry = sum / 10;
+    }
+    return result;
+}
+
+std::string BigInteger::subAbs(const std::string& a, const std::string& b) {
+    std::string ta = trimLeadingZeros(a);
+    std::string tb = trimLeadingZeros(b);
+    if (compareAbs(ta, tb) < 0) {
+        return subAbs(tb, ta);
+    }
+    std::string result;
+    int borrow = 0;
+    int i = static_cast<int>(ta.size()) - 1;
+    int j = static_cast<int>(tb.size()) - 1;
+    while (i >= 0) {
+        int diff = (ta[i--] - '0') - borrow;
+        if (j >= 0) {
+            diff -= (tb[j--] - '0');
+        }
+        if (diff < 0) {
+            diff += 10;
+            borrow = 1;
+        } else {
+            borrow = 0;
+        }
+        result = char('0' + diff) + result;
+    }
+    return trimLeadingZeros(result);
+}
+
+std::string BigInteger::mulAbs(const std::string& a, const std::string& b) {
+    std::string ta = trimLeadingZeros(a);
+    std::string tb = trimLeadingZeros(b);
+    if (ta == "0" || tb == "0") return "0";
+
+    std::vector<int> product(ta.size() + tb.size(), 0);
+    for (size_t i = 0; i < ta.size(); i++) {
+        for (size_t j = 0; j < tb.size(); j++) {
+            int mul = (ta[ta.size() - 1 - i] - '0') * (tb[tb.size() - 1 - j] - '0');
+            product[i + j] += mul;
+        }
+    }
+
+    int carry = 0;
+    for (size_t i = 0; i < product.size(); i++) {
+        int sum = product[i] + carry;
+        product[i] = sum % 10;
+        carry = sum / 10;
+    }
+
+    std::string result;
+    for (int i = static_cast<int>(product.size()) - 1; i >= 0; i--) {
+        result += char('0' + product[i]);
+    }
+    return trimLeadingZeros(result);
+}
+
+std::string BigInteger::divAbs(const std::string& a, const std::string& b) {
+    std::string tb = trimLeadingZeros(b);
+    if (tb == "0") {
+        throw std::invalid_argument("division by zero");
+    }
+    std::string ta = trimLeadingZeros(a);
+    if (compareAbs(ta, tb) < 0) {
+        return "0";
+    }
+
+    std::string quotient;
+    std::string current;
+    for (char digit : ta) {
+        current += digit;
+        current = trimLeadingZeros(current);
+        int count = 0;
+        while (compareAbs(current, tb) >= 0) {
+            current = subAbs(current, tb);
+            count++;
+        }
+        quotient += char('0' + count);
+    }
+    return trimLeadingZeros(quotient);
+}
+
+BigInteger::BigInteger() : digits_("0"), sign_(0) {}
+
+BigInteger::BigInteger(int value) : digits_("0"), sign_(1) {
+    if (value == 0) {
+        digits_ = "0";
+        sign_ = 0;
+        return;
+    }
+    if (value < 0) {
+        sign_ = -1;
+        value = -value;
+    }
+    digits_.clear();
+    while (value > 0) {
+        digits_ = char('0' + value % 10) + digits_;
+        value /= 10;
+    }
+}
+
+BigInteger::BigInteger(long long value) : digits_("0"), sign_(1) {
+    if (value == 0) {
+        digits_ = "0";
+        sign_ = 0;
+        return;
+    }
+    if (value < 0) {
+        sign_ = -1;
+        value = -value;
+    }
+    digits_.clear();
+    while (value > 0) {
+        digits_ = char('0' + value % 10) + digits_;
+        value /= 10;
+    }
+}
+
+BigInteger::BigInteger(unsigned long long value) : digits_("0"), sign_(1) {
+    if (value == 0) {
+        digits_ = "0";
+        sign_ = 0;
+        return;
+    }
+    digits_.clear();
+    while (value > 0) {
+        digits_ = char('0' + value % 10) + digits_;
+        value /= 10;
+    }
+}
+
+BigInteger::BigInteger(const std::string& value) : digits_("0"), sign_(1) {
+    if (value.empty()) {
+        digits_ = "0";
+        sign_ = 0;
+        return;
+    }
+
+    std::string text = value;
+    sign_ = 1;
+
+    if (text[0] == '-') {
+        sign_ = -1;
+        text = text.substr(1);
+    } else if (text[0] == '+') {
+        text = text.substr(1);
+    }
+
+    if (text.empty()) {
+        digits_ = "0";
+        sign_ = 0;
+        return;
+    }
+
+    for (char ch : text) {
+        if (ch < '0' || ch > '9') {
+            throw std::invalid_argument("BigInteger: invalid numeric string");
+        }
+    }
+
+    digits_ = trimLeadingZeros(text);
+    if (digits_ == "0") {
+        sign_ = 0;
+    }
+}
+
+BigInteger::BigInteger(const char* value)
+    : BigInteger(value == nullptr ? std::string("0") : std::string(value)) {}
+
+bool BigInteger::isZero() const {
+    return sign_ == 0 || digits_ == "0";
+}
+
+int BigInteger::sign() const {
+    return isZero() ? 0 : sign_;
+}
+
+std::string BigInteger::toString() const {
+    if (isZero()) return "0";
+    return (sign_ < 0 ? "-" : "") + digits_;
+}
+
+bool BigInteger::operator==(const BigInteger& other) const {
+    if (isZero() && other.isZero()) return true;
+    return sign_ == other.sign_ && digits_ == other.digits_;
+}
+
+bool BigInteger::operator!=(const BigInteger& other) const {
+    return !(*this == other);
+}
+
+bool BigInteger::operator<(const BigInteger& other) const {
+    if (sign_ != other.sign_) return sign_ < other.sign_;
+    if (sign_ == 0) return false;
+    int cmp = compareAbs(digits_, other.digits_);
+    return sign_ > 0 ? cmp < 0 : cmp > 0;
+}
+
+bool BigInteger::operator>(const BigInteger& other) const {
+    return other < *this;
+}
+
+bool BigInteger::operator<=(const BigInteger& other) const {
+    return *this < other || *this == other;
+}
+
+bool BigInteger::operator>=(const BigInteger& other) const {
+    return other <= *this;
+}
+
+bool BigInteger::operator==(int value) const {
+    return *this == BigInteger(value);
+}
+
+bool BigInteger::operator!=(int value) const {
+    return !(*this == value);
+}
+
+bool BigInteger::operator<(int value) const {
+    return *this < BigInteger(value);
+}
+
+bool BigInteger::operator>(int value) const {
+    return *this > BigInteger(value);
+}
+
+bool BigInteger::operator<=(int value) const {
+    return *this <= BigInteger(value);
+}
+
+bool BigInteger::operator>=(int value) const {
+    return *this >= BigInteger(value);
+}
+
+bool BigInteger::operator==(long long value) const {
+    return *this == BigInteger(value);
+}
+
+bool BigInteger::operator!=(long long value) const {
+    return !(*this == value);
+}
+
+bool BigInteger::operator<(long long value) const {
+    return *this < BigInteger(value);
+}
+
+bool BigInteger::operator>(long long value) const {
+    return *this > BigInteger(value);
+}
+
+bool BigInteger::operator<=(long long value) const {
+    return *this <= BigInteger(value);
+}
+
+bool BigInteger::operator>=(long long value) const {
+    return *this >= BigInteger(value);
+}
+
+BigInteger BigInteger::operator+() const {
+    return *this;
+}
+
+BigInteger BigInteger::operator-() const {
+    if (isZero()) return BigInteger(0);
+    BigInteger result(*this);
+    result.sign_ = -result.sign_;
+    return result;
+}
+
+BigInteger& BigInteger::operator+=(const BigInteger& other) {
+    *this = *this + other;
+    return *this;
+}
+
+BigInteger& BigInteger::operator-=(const BigInteger& other) {
+    *this = *this - other;
+    return *this;
+}
+
+BigInteger& BigInteger::operator*=(const BigInteger& other) {
+    *this = *this * other;
+    return *this;
+}
+
+BigInteger& BigInteger::operator/=(const BigInteger& other) {
+    *this = *this / other;
+    return *this;
+}
+
+BigInteger BigInteger::operator+(const BigInteger& other) const {
+    if (isZero()) return other;
+    if (other.isZero()) return *this;
+
+    BigInteger result;
+    if (sign_ == other.sign_) {
+        result.digits_ = addAbs(digits_, other.digits_);
+        result.sign_ = sign_;
+    } else {
+        int cmp = compareAbs(digits_, other.digits_);
+        if (cmp == 0) {
+            result.digits_ = "0";
+            result.sign_ = 0;
+        } else if (cmp > 0) {
+            result.digits_ = subAbs(digits_, other.digits_);
+            result.sign_ = sign_;
+        } else {
+            result.digits_ = subAbs(other.digits_, digits_);
+            result.sign_ = other.sign_;
+        }
+    }
+    if (result.digits_ == "0") result.sign_ = 0;
+    return result;
+}
+
+BigInteger BigInteger::operator-(const BigInteger& other) const {
+    return *this + (-other);
+}
+
+BigInteger BigInteger::operator*(const BigInteger& other) const {
+    if (isZero() || other.isZero()) return BigInteger(0);
+    BigInteger result;
+    result.digits_ = mulAbs(digits_, other.digits_);
+    result.sign_ = (sign_ * other.sign_);
+    if (result.digits_ == "0") result.sign_ = 0;
+    return result;
+}
+
+BigInteger BigInteger::operator/(const BigInteger& other) const {
+    if (other.isZero()) {
+        throw std::invalid_argument("division by zero");
+    }
+    if (isZero()) return BigInteger(0);
+    BigInteger result;
+    result.digits_ = divAbs(digits_, other.digits_);
+    result.sign_ = (sign_ * other.sign_);
+    if (result.digits_ == "0") result.sign_ = 0;
+    return result;
+}
+
+} // namespace bstl
+
diff --git a/tests/BigDecimalTest.cpp b/tests/BigDecimalTest.cpp
new file mode 100644
index 0000000..8a14df4
--- /dev/null
+++ b/tests/BigDecimalTest.cpp
@@ -0,0 +1,41 @@
+#include <BigDecimal.hpp>
+
+#include <cassert>
+#include <iostream>
+#include <string>
+
+int main() {
+    using bstl::BigDecimal;
+
+    // 基本构造
+    BigDecimal a("123.45");
+    BigDecimal b("67.89");
+    BigDecimal c = a + b;
+
+    assert(c.toString() == "191.34");
+
+    // 减法
+    BigDecimal d = a - b;
+    assert(d.toString() == "55.56");
+
+    // 乘法
+    BigDecimal e = a * BigDecimal("2");
+    assert(e.toString() == "246.90");
+
+    // 比较
+    assert((a > b) == true);
+    assert((a == a) == true);
+    assert((a != b) == true);
+
+    // 零
+    BigDecimal zero("0.0");
+    assert(zero.isZero());
+
+    // 负数
+    BigDecimal neg("-100.50");
+    assert(neg.sign() < 0);
+    assert((-neg).toString() == "100.50");
+
+    std::cout << "BigDecimal tests passed\n";
+    return 0;
+}
diff --git a/tests/BigIntegerTest.cpp b/tests/BigIntegerTest.cpp
new file mode 100644
index 0000000..475478b
--- /dev/null
+++ b/tests/BigIntegerTest.cpp
@@ -0,0 +1,31 @@
+#include <BigInteger.hpp>
+
+#include <cassert>
+#include <iostream>
+#include <string>
+
+int main() {
+    using bstl::BigInteger;
+
+    BigInteger a("12345678901234567890");
+    BigInteger b("98765432109876543210");
+    BigInteger c = a + b;
+    BigInteger d = b - a;
+    BigInteger e = a * BigInteger("2");
+    BigInteger f = BigInteger("100000000000000000000000") / BigInteger("1000000000000000000");
+
+    assert(c.toString() == "111111111011111111100");
+    assert(d.toString() == "86419753208641975320");
+    assert(e.toString() == "24691357802469135780");
+    assert(f.toString() == "100000");
+
+    BigInteger zero("0");
+    assert((a == a) == true);
+    assert((a != b) == true);
+    assert((zero == 0) == true);
+    assert((a > BigInteger("12345678901234567889")) == true);
+    assert((a < b) == true);
+
+    std::cout << "BigInteger tests passed\n";
+    return 0;
+}