C++如何替换字符串中的字符？

std::string str = "hello";
str[0] = 'H';  // 将第一个字符 h 改为 H
// 结果：str 变为 "Hello"

std::string str = "apple";
for (char& c : str) {
    if (c == 'a') {
        c = 'A';
    }
}
// 结果：str 变为 "Apple"

#include <algorithm>
std::string str = "banana";
std::replace(str.begin(), str.end(), 'a', '@');
// 结果：str 变为 "b@n@n@"

std::string str = "Hello, world! Welcome to the world of C++";

size_t pos = 0;
std::string target = "world";
std::string replacement = "universe";

while ((pos = str.find(target, pos)) != std::string::npos) {
    str.replace(pos, target.length(), replacement);
    pos += replacement.length(); // 跳过已替换部分，防止死循环
}
// 结果：所有 "world" 被替换为 "universe"

void replaceAll(std::string& str, const std::string& from, const std::string& to) {
    size_t pos = 0;
    while ((pos = str.find(from, pos)) != std::string::npos) {
        str.replace(pos, from.length(), to);
        pos += to.length();
    }
}

std::string text = "I love coding. coding is fun!";
replaceAll(text, "coding", "programming");
// 结果："I love programming. programming is fun!"