有符号/无符号比较警告是什么意思? [英] what does the signed/unsigned comparison warning mean?

问题描述

auto.cpp: In function ‘int autooo(unsigned int)’:
auto.cpp:33:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]

我正在做makefile文件，并且我已经运行了makefile文件并创建了一个auto.o文件，但仍然出现此错误，下面是我的autooo.cpp文件，auto.h文件

im doing the makefile , and i already run the makefile and make an auto.o but still i get this error, below is my autooo.cpp , auto.h

我不理解未签名和已签名的内容:\请帮助

i dont undestand what is unsigned and signed :\ please help

auto.h

#ifndef function_H_
#define function_H_

int autooo(unsigned);
int interr(unsigned);


#endif /* function_H_ */

autooo.cpp

autooo.cpp

#include <iostream>   
#include <cstdlib>  //for random functions
#include "prime.h"
#include "auto.h"
using namespace std;


#ifndef auto_CPP_
#define auto_CPP_

int autooo(unsigned);

int autooo(unsigned a)
{       
    int b=50;
    unsigned numberFound = 0;

    do
    {    
        ++a;    

        if (isPrime(a))    
        {    
            ++numberFound;    
            cout << a << "is prime number" <<endl;    
        }    
    } while (numberFound < b);

    return 0;
}

#endif

推荐答案

编译器警告该代码在行中包含 unsigned int 与 signed int 的比较

The compiler warns that the code contains comparison of unsigned int with a signed int in the line

while (numberFound < b);

这与makefile或make无关.

This has nothing to do with makefiles or make.

您可以通过更改来解决

int b=50;

到

unsigned b = 50;

或通过更改

unsigned numberFound = 0;

到

int numberFound = 0;

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