C++ strcmp 无法将 'std::string {aka std::basic_string<char>}' 转换为 'const char*
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strcmp cannot convert ‘std::string {aka std::basic_string<char>}’ to ‘const char*
提问by Jonathon Reinhart
Apologies in advance for the elementary nature of the question.
提前为问题的基本性质道歉。
I am trying to use the strcmpfunction to test two strings for matching characters.
我正在尝试使用该strcmp函数来测试两个字符串的匹配字符。
I reduced the issue to the simple code below:
我将问题简化为下面的简单代码：
#include <iostream>
#include <cstring>
using namespace std;
void compareStrings(string, string);
int main()
{
string string1 = "testString", string2 = "testString";
compareStrings(string1, string2);
return 0;
}
void compareStrings(string stringOne, string stringTwo)
{
if (strcmp(stringOne,stringTwo) == 0)
cout << "The strings match." << endl;
else
cout << "The strings don't match." << endl;
}
Could someone explain the following compiler error message?
有人可以解释以下编译器错误消息吗？
./newProgram.cpp: In function ‘void compareStrings(std::string, std::string)':
./newProgram.cpp:17:32: error: cannot convert ‘std::string {aka std::basic_string<char>}' to ‘const char*' for argument ‘1' to ‘int strcmp(const char*, const char*)'
if (strcmp(stringOne,stringTwo) == 0)
^
Thanks! Xz.
谢谢！XZ。
回答by Jonathon Reinhart
strcmpis for C strings (null-terminated char *). string::compareis for C++ strings.
strcmp用于 C 字符串（以空字符结尾char *）。 string::compare用于 C++ strings。
If you reallywant to use strcmpwith your std::string, you can use string::c_str()to get a pointer to the underlying C-string:
如果您真的想strcmp与您的一起使用std::string，您可以使用string::c_str()来获取指向底层 C 字符串的指针：
if (strcmp(stringOne.c_str(), stringTwo.c_str()) == 0)
But of course, if you're using C++, you should actually useC++, and make use of std::string's ==overload.
但是，当然，如果您使用 C++，您实际上应该使用C++，并利用std::string的==重载。
if (stringOne == stringTwo)
