View Compilation Error

0_0_25927204_16544.c: In function 'update':
0_0_25927204_16544.c:14:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = k;i <= n;i += lowbit(i))
     ^
0_0_25927204_16544.c:14:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_25927204_16544.c: In function 'getsum':
0_0_25927204_16544.c:20:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i = x;i;i -= lowbit(i))
     ^