Need explanation for C output

Question

Possible Duplicate:
What is the difference between char a[] = “string”; and char *p = “string”;

int main() {
 char *p="ayqm";
 char c;
 c=++*p;
 printf("%c",c);
 return 0;
}

Its output is a. See http://codepad.org/cbNOPuWt But I feel that the output should be b since c = ++*p. Anybody can explain the reason for the output?

score 6 · Accepted Answer · answered Nov 20 '12 at 04:41

6

Sure, it's undefined behavior. Anything can happen.

You're attempting to modify a string literal, which is illegal.

If you do, for example

char c = *p;
++c;

you'll see the correct output.

The actual type of p should be const char*, in which case you'd get a compiler error.

answered Nov 20 '12 at 04:41

Luchian Grigore

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Augh! Beat me to it by a second :) – Reuben Morais Nov 20 '12 at 04:44
@habeebperwad you could see it as that, yes. But `++'a'` is also illegal. – Luchian Grigore Nov 20 '12 at 04:58

Need explanation for C output

1 Answers1