View Compilation Error

0_0_31838855_28594.c: In function 'main':
0_0_31838855_28594.c:10:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i=0;i<strlen(str);i++){
     ^
0_0_31838855_28594.c:10:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code