condition is false but even then its printing size of s-CodePudding

#include<stdio.h>
#include<string.h>

void printlen(char *s,char *t){
    int c=0;
    int len=((strlen(s)-strlen(t)>c)?strlen(s):strlen(t));
    printf("%d",len);
}

void main(){

char *x="abc";
char *y="defgh";
   printlen(x,y);

}

strlen(s) is 3 and strlen(t) is 5, so why is strlen(s)-strlen(t)>c evaluating to true?

CodePudding user response：

The strlen function returns a value of type size_t which is unsigned.

So subtracting unsigned 3 from unsigned 5 results in a very large unsigned number. This number is greater than 0 so the condition is true, causing strlen(s) to be evaluated and assigned to len.

The result of the subtraction should be cast to int to properly store a signed value.

int len=(((int)(strlen(s)-strlen(t))>c)?strlen(s):strlen(t));

CodePudding user response：

int len=((strlen(s)-strlen(t)>c)?strlen(s):strlen(t));
printf("%d",len);

is equal:

int len;

if((strlen(s) - strlen(t) > c)
    len = strlen(s);
else
    len = strlen(t);
printf("%d",len);

Firstly, printf("%d",len); is unconditional. Whatever len(s) - strlen(t) > c is true or false, printf("%d",len); get executed.

Second, strlen return size_t, which is an alias for unsigned int, so (strlen(s) - strlen(t) > c) is always true.

You should typecast it to an int

int len=(((int)strlen(s)-strlen(t)>c)?strlen(s):strlen(t));