View Compilation Error

0_0_26337065_714.c: In function 'main':
0_0_26337065_714.c:8:1: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
 for(int i=0;i<cout;i++)
 ^
0_0_26337065_714.c:8:1: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_26337065_714.c:10:1: error: 'sum' undeclared (first use in this function)
 sum+=num;
 ^
0_0_26337065_714.c:10:1: note: each undeclared identifier is reported only once for each function it appears in