View Compilation Error

0_0_34841610_6157.c: In function 'main':
0_0_34841610_6157.c:14:10: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
          for(int i=0; i<strlen(ch);i++)
          ^
0_0_34841610_6157.c:14:10: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_34841610_6157.c:58:14: error: redefinition of 'i'
          int i=0;
              ^
0_0_34841610_6157.c:14:18: note: previous definition of 'i' was here
          for(int i=0; i<strlen(ch);i++)
                  ^