c - I am getting a value from a function without return -

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• function returns value without return statement 5 answers

i know happening in simple c code:

#include <stdio.h> int something(int a, int b) {     int c = * 3 + 4 * b; } int main() {     int res = something(12, 54);     printf("%d\n", res);         return 0; } 

the function not have return, "res" stores value calculated in something.

following show compilation command, execution , output:

$ gcc main.c

$ ./a.out

252

---

edited

i have changed variables types int float, in relation @paul ogilvie comment, , seems return last int stored:

#include <stdio.h> float something(int a, int b) {     float res = * 3 + 4 * b * 1.0; } int main() {     float res = something(12, 54);     printf("%d\n", res);     return 0; } 

$ gcc main.c

$ ./a.out

54

it undefined behavior, see here:

reaching end of other value-returning function undefined behavior, if result of function used in expression.

compiling code gcc -wreturn-type gives appropriate warning:

ret.c:4:1: warning: control reaches end of non-void function [-wreturn-type]