C++测试代码

Question

这是以二进制形式打印“c++”并同时测量时间的代码

#include <iostream>
#include <string>
#include <cstdlib>
#include <ctime>
using namespace std;

int main(){
    unsigned int t = clock();
    string c = "c++";
    int t=0;
    for (int i=0;i<c.length();i++){
        t = (int) c[i];
        while (t!=0){
            cout << t % 2 <<endl;
            t >>= 1;
        }
    }
    unsigned int end = clock();
    cout << end-t << endl;
    return 0;
}

但是这里是错误的

1>------ Build started: Project: name_of_c++, Configuration: Debug Win32 ------
1>  c++_name.cpp
1>c:\users\david\documents\visual studio 2010\projects\name_of_c++\c++_name.cpp(11): error C2371: 't' : redefinition; different basic types
1>          c:\users\david\documents\visual studio 2010\projects\name_of_c++\c++_name.cpp(7) : see declaration of 't'
1>c:\users\david\documents\visual studio 2010\projects\name_of_c++\c++_name.cpp(12): warning C4018: '<' : signed/unsigned mismatch
1>c:\users\david\documents\visual studio 2010\projects\name_of_c++\c++_name.cpp(16): error C2059: syntax error : '>='
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

Answer 1

看这两行:

unsigned int t=clock();
int t=0;

它们都在同一个范围内，都定义了一个变量t。这在 C++ 中是不允许的!

如果您在解析错误消息时遇到问题，当您收到类似以下内容时:

c++_name.cpp(11): error C2371: 't' : redefinition; different basic types

括号中的数字 (11) 告诉您发生错误的行。