Why Is Comparing if an Unsigned Int >= 0 a “Pointless Comparison”?

Question

I got warning:

Pe186 \"Pointless comparison of unsigned int with zero\"

when I tried to compile the following code:

Answer 1

The warning complains about your for loop break condition clLoop >= 0. The loop will end if clLoop gets negative, but that will never happen for an unsigned int.

Answer 2

You should remove = in

clLoop >= 0

Let's say your cpLoopStart is 5.

Then, clLoop value in the further iteratiosn would be -

clLoop = 4;
clLoop = 3;
clLoop = 2;
clLoop = 1;
clLoop = 0;
clLoop = 0;
clLoop = 0;
clLoop = 0;
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Infinite times.

Answer 3

do{} while() can help you to use unsigned types of variable for loop without integer overflow:

// main.c
#include <stdio.h>

int main(void)
{

    int array[] = {1,2,3,4,5,6,7,8,9,10};
    unsigned int size = sizeof(array)/sizeof(int); // size == 10;

    unsigned int i = size;
    do
    {
        i--;
        printf("Index: %u, content: %d\n",i,array[i]);

    } while(i > 0);

    return 0;
}

And compile it with:

gcc -std=c11 -Wall -Wextra -Wpedantic main.c

Output:

Index: 9, content: 10
Index: 8, content: 9
Index: 7, content: 8
Index: 6, content: 7
Index: 5, content: 6
Index: 4, content: 5
Index: 3, content: 4
Index: 2, content: 3
Index: 1, content: 2
Index: 0, content: 1

Answer 4

I think you meant to say

for(clLoop = cpLoopStart; clLoop; clLoop--)                                  
{ //Do something
}