CODEWITHSUNDEEP
cfor-loop
guitar_geek
guitar_geek

Reputation: 498

condition check in for loop in C

Suppose I have a string "str". My for loop is as follows: 

 for(i=0;i<strlen(str);i++){

    //do stuff

 }

question: When the condition is checked ,i < strlen(str), is the strlen(str) part calculated each time the loop runs ? Or it gets stored and is computed for the first time only?

Upvotes: 0

Views: 2339

Answers (1)

&#211;scar L&#243;pez
&#211;scar L&#243;pez

Reputation: 235984

The condition expression in a loop will get evaluated at each and every iteration - it has to be that way until (ideally) the expression becomes false. So yes: strlen(str) will be calculated over and over again. If the string doesn't change at all, it'll be better if you store its length in a local variable.

int n = strlen(str);
for (i=0; i<n; i++) {
    // do stuff
}

This will also work:

for (i=0; str[i] != '\0'; i++) {
    // do stuff
}

Upvotes: 5

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