c - difference between return 1, return 0 and return -1 and exit? -

for example consider following code

int main(int argc,char *argv[]) {    int *p,*q;    p = (int *)malloc(sizeof(int)*10);    q = (int *)malloc(sizeof(int)*10);    if (p == 0) {     printf("error: out of memory\n");         return 1; }      if (q == 0) {     printf("error: out of memory\n");         exit(0); }     return 0; } 

what return 0,return 1,exit(0) in above program.. exit(0) exit total program , control comes out of loop happens in case of return 0,return 1,return -1.

return main() equivalent exit

the program terminates execution exit status set value passed return or exit

return in inner function (not main) terminate execution of specific function returning given result calling function.

exit anywhere on code terminate execution immediately.

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status 0 means program succeeded.

status different 0 means program exited due error or anomaly.

if exit status different 0 you're supposed print error message stderr instead of using printf better like

if(erroroccurred) {     fprintf(stderr, "meaningful message here\n");     return -1; } 

note (depending on os you're on) there conventions return codes.

also os may terminate program specific exit status codes if attempt invalid operations reading memory have no access to.

google "exit status codes" or similar , you'll find plenty of information on , elsewhere.