Compiler Error 77 D

This can happen if you've put a statement (eg an assignment) outside of any function:

#include "mbed.h"

DigitalOut myled(LED1);

/* This will cause an error - statements must live inside functions */
myled =0 ;

int main() {
    while(1) {
        myled = 1;
        wait(0.2);
        myled = 0;
        wait(0.2);
    }
}

You can initialise variables either as part of their declaration for simple types:

...
int i = 0;
...

...or inside the main function:

#include "mbed.h"

DigitalOut myled(LED1);

int main() {
    /* This will succeed */
    myled =0 ;
    while(1) {
        myled = 1;
        wait(0.2);
        myled = 0;
        wait(0.2);
    }
}
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