How to inspect the return value of a function in GDB?

Question

Is it possible to inspect the return value of a function in gdb assuming the return value is not assigned to a variable?

Answer 1

I imagine there are better ways to do it, but the finish command executes until the current stack frame is popped off and prints the return value -- given the program

int fun() {     return 42; }  int main( int argc, char *v[] ) {     fun();     return 0; } 

You can debug it as such --

(gdb) r Starting program: /usr/home/hark/a.out   Breakpoint 1, fun () at test.c:2 2               return 42; (gdb) finish Run till exit from #0  fun () at test.c:2 main () at test.c:7 7               return 0; Value returned is $1 = 42 (gdb)  

The finish command can be abbreviated as fin. Do NOT use the f, which is abbreviation of frame command!