loops - Converting this code line to C

Question

I have the following code line:

for ( int i = index; i < al->size; ++i )

//i,index and size are integers.al is an arraylist

When I compile this in C, I get the error:

 'for' loop initial declarations are only allowed in C99 mode

Im not sure on how to fix this.

Thank you!

Answer 1

Either declare the iterator outside of the loop:

int i;

for (i = index; i < al->size; ++i) {
    do_foo();
}

or if your compiler supports it, compile against the c99 or compatible standard:

gcc -std=c99 your_code.c 

(Note that gnu89/gnu90 is the default (as of 4.8, anyway.))