How to compile a C project in C99 mode?

Question

I got the following error message while compiling the C code:

error: \'for\' loop initial declarations are only allowed in C99 mode
note: use option -std=c9         


        

Answer 1

It means you can't declare variables in for statement.

You should do:

int i ;
for( i = 0 ; i < len ; i++ )

What you are probably doing

for( int i = 0 ; i < len ; i++ )