Question

The following C program:

int doStuff(int afm[]);

int main(){
    int afm1[9] = {1,2,3,4,5,6,7,8,9}; //size=9

    int afmLength = sizeof(afm1)/sizeof(int);
    printf("main: Length Of Array=%d\n", afmLength);  //9 OK

    int k = doStuff(afm1);

    system("PAUSE");
    return 0;   
}

int doStuff(int afm[]){
    int afmLength = sizeof(afm)/sizeof(int);    
    printf("doStuff: Length Of Array=%d\n", afmLength);  //1 WRONG

    return 1;
}

produces the following output:

main: Length Of Array=9
doStuff: Length Of Array=1

Why is the array size calculated correctly in main, but is wrong inside the function?

Answer 1

Because in main you have an array and in the function you have a pointer to that array.

int doStuff(int afm[])

is equivalent to

int doStuff(int *afm)