View Compilation Error

0_0_27206031_20952.c: In function 'insert':
0_0_27206031_20952.c:9:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i=0;i<50000;i++)
     ^
0_0_27206031_20952.c:9:5: note: use option -std=c99, -std=gnu99, -std=c11 or -std=gnu11 to compile your code
0_0_27206031_20952.c: In function 'calculate':
0_0_27206031_20952.c:23:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i=L-1;i<R;i++)
     ^
0_0_27206031_20952.c:27:13: error: redefinition of 'i'
     for(int i=0;b[i]>=0;i++)
             ^
0_0_27206031_20952.c:23:13: note: previous definition of 'i' was here
     for(int i=L-1;i<R;i++)
             ^
0_0_27206031_20952.c:27:5: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
     for(int i=0;b[i]>=0;i++)
     ^
0_0_27206031_20952.c: In function 'main':
0_0_27206031_20952.c:41:9: error: 'for' loop initial declarations are only allowed in C99 or C11 mode
         for(int i=0;i<n;i++)
         ^