sine_print.c

#include <stdio.h>
#include <math.h>
#include <string.h>

int main()
{
    int i;
    int offset;
    char sinstr[80];

    memset(sinstr,0x20, 80);
    sinstr[79] = '\0';

    for (i = 0; i < 20; i++) {
        offset = 39 + (int)(39 * sin(M_PI * (float) i/10)):

        sinstr[offset] = '*';
        printf("%s\n", sinstr);
        sinstr[offset] = ' ';
    }
}