foo.c: In function 'main':
foo.c:9:2: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:9:2: note: use option -std=c99 or -std=gnu99 to compile your code
foo.c:10:2: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:12:3: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:14:2: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:16:1: warning: control reaches end of non-void function [-Wreturn-type]