View Compilation Error

0_0_18558572_32295.c: In function 'main':
0_0_18558572_32295.c:12:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int k=0; k<n; k++)
         ^
0_0_18558572_32295.c:12:9: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_18558572_32295.c:22:13: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
             for(int i=1; i<length; i++)
             ^
0_0_18558572_32295.c:31:21: error: redefinition of 'i'
             for(int i=0;i<length;i++)
                     ^
0_0_18558572_32295.c:22:21: note: previous definition of 'i' was here
             for(int i=1; i<length; i++)
                     ^
0_0_18558572_32295.c:31:13: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
             for(int i=0;i<length;i++)
             ^