C++ 如何修复“没有匹配的函数调用‘atoi’”错误？

How do I fix a "no matching function for call to 'atoi'" error?

提问by nipponese

All indications tell me this is a ridiculously easy problem to solve, but I can't figure out error telling me the atoifunction doesn't exist.

所有迹象都告诉我这是一个非常容易解决的问题，但我无法弄清楚错误告诉我该atoi函数不存在。

C++

C++

#include <iostream>
#include <stdlib.h>

using namespace std;

string line;
int i;

int main() {

    line = "Hello";
    i = atoi(line);
    cout << i;

    return 0;
}

Error

错误

lab.cpp:18:6: error: no matching function for call to 'atoi'
i = atoi(line);
    ^~~~

回答by juanchopanza

atoiexpects const char*, not an std::string. So pass it one:

atoi预计const char*，而不是std::string. 所以通过它：

i = atoi(line.c_str());

Alternatively, use std::stoi:

或者，使用std::stoi：

i = std::stoi(line);

回答by Nassim

You have to use

你必须使用

const char *line = myString.c_str();

instead of:

代替：

std::string line = "Hello";

since atoi won't accept an std::string

因为 atoi 不会接受 std::string