一文带你了解C++中的字符替换方法

#include <algorithm>
 
// ...
 
std::string str = "Hello, World!";
std::replace(str.begin(), str.end(), 'o', 'O');
 
// str 现在为 "HellO, WOrld!"

std::string str = "Hello, World!";
 
for (char& c : str) {
    if (c == 'o') {
        c = 'O';
    }
}
 
// str 现在为 "HellO, WOrld!"

#include <regex>
 
// ...
 
std::string str = "Hello, World!";
std::string result = std::regex_replace(str, std::regex("o"), "O");
 
// result 现在为 "HellO, WOrld!"

#include <sstream>
#include <string>
 
std::string replace(std::string str, const std::string& from, const std::string& to) {
    std::stringstream ss;
    size_t start_pos = 0;
    while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
        ss << str.substr(0, start_pos) << to;
        start_pos += from.length();
        str = str.substr(start_pos);
    }
    ss << str;
    return ss.str();
}
 
int main() {
    std::string str = "Hello, World!";
    std::string from = "World";
    std::string to = "C++";
    std::string result = replace(str, from, to);
    std::cout << result << std::endl;  // 输出：Hello, C++!
    return 0;
}

#include <iostream>
#include <cstring>
 
char* replace(char* str, const char* from, const char* to) {
    size_t str_len = strlen(str);
    size_t from_len = strlen(from);
    size_t to_len = strlen(to);
    size_t new_len = str_len + to_len - from_len;
    char* new_str = new char[new_len + 1];
    char* p1 = str;
    char* p2 = new_str;
    while (*p1) {
        if (strncmp(p1, from, from_len) == 0) {
            strncpy(p2, to, to_len);
            p2 += to_len;
            p1 += from_len;
        } else {
            *p2++ = *p1++;
        }
    }
    *p2 = '\0';
    delete[] str;
    return new_str;
}
 
int main() {
    char str[] = "Hello, World!";
    const char* from ="World";
    const char* to = "C++";
    char* result = replace(str, from, to);
    std::cout << result << std::endl; // 输出：Hello, C++!
    delete[] result;
    return 0;
}

#include <algorithm>
#include <string>
 
std::string replace(std::string str, const std::string& from, const std::string& to) {
    size_t start_pos = 0;
    while ((start_pos = str.find(from, start_pos)) != std::string::npos) {
        str.replace(start_pos, from.length(), to);
        start_pos += to.length();
    }
    return str;
}
 
int main() {
    std::string str = "Hello, World!";
    std::string from = "World";
    std::string to = "C++";
    std::string result = replace(str, from, to);
    std::cout << result << std::endl;  // 输出：Hello, C++!
    return 0;
}

#include <regex>
#include <string>
 
std::string replace(std::string str, const std::string& pattern, const std::string& to) {
    std::regex r(pattern);
    return std::regex_replace(str, r, to);
}
 
int main() {
    std::string str = "Hello, World!";
    std::string str = "Hello, World!";
    std::string result = replace(str, "World", "C++");  // 替换所有的 "World" 为 "C++"
    std::cout << result << std::endl;  // 输出：Hello, C++!
 
    result = replace(str, "[Ww]orld", "C++");  // 替换所有的 "World" 或 "world" 为 "C++"
    std::cout << result << std::endl;  // 输出：Hello, C++!
 
    result = replace(str, "[a-zA-Z]+", "C++");  // 替换所有的单词为 "C++"
    std::cout << result << std::endl;  // 输出：C++, C++!
 
    result = replace(str, "\\b\\w+\\b", "C++");  // 同上
    std::cout << result << std::endl;  // 输出：C++, C++!
}