c++ testing code

Question

here is code which print "c++" in binary form and at the same time measure time

#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;
}

but here is mistake

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

Look at these two lines:

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

These are both in the same scope, and both define a variable t . This is not allowed in C++!

In case you are having trouble parsing the error message, when you get something like:

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

The number in parenthesis (11) tells you the line where the error occurred.

Answer 2

You know, compiler prints line numbers for errors.

Here is a problem:

unsigned int t=clock();


string c="c++";
int t=0;

First you declare t as unsigned int, and then you declare it as int.

Answer 3

you have declared t as unsigned int first here:

unsigned int t=clock();

and then defined again here as int

 int t=0;

You can use a different variable name for the second one to get rid of this error.