Question

The code given here when compiled by g++ runs fine but gives error on compiling with gcc. Obviously, this is correct for C++ but not for C. Please help me to correct the syntax for C.

# include <stdio.h>
typedef struct demo
{
    int arr[20], i;
    void setvalue(int num)
    {for(i=0;i<20;i++)arr[i]=num;}

    void printvalue()
    {for(i=0;i<20;i++)printf("%d ",arr[i]);}
} example;

int main()
{
    example e;
    e.setvalue(100);
    e.printvalue();
    return 0;
}

Error log:

stov.c:7:2: error: expected ‘:’, ‘,’, ‘;’, ‘}’ or ‘__attribute__’ before ‘{’ token
stov.c: In function ‘main’:
stov.c:18:3: error: ‘example’ has no member named ‘setvalue’
stov.c:19:3: error: ‘example’ has no member named ‘printvalue’

Answer 1

You can’t have methods in C (that function in the struct). There’s more than one way to solve this, but I would simply pass the object as the first argument to the function:

void setvalue(struct demo *d, int num)
{
    int i;
    for(i = 0; i < 20; i++)
        d->arr[i] = num;
}


/* ... */
setvalue(&e, 100);