foo.c: In function 'main':
foo.c:16:1: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:16:1: note: use option -std=c99 or -std=gnu99 to compile your code
foo.c:23:9: error: redefinition of 'i'
foo.c:16:9: note: previous definition of 'i' was here
foo.c:23:1: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:32:9: error: redefinition of 'i'
foo.c:23:9: note: previous definition of 'i' was here
foo.c:32:1: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:34:1: error: 'for' loop initial declarations are only allowed in C99 mode
foo.c:48:1: warning: control reaches end of non-void function [-Wreturn-type]