sin.c

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

char wav_to_char(const float f)
{
  return "_,.-*`''"[(unsigned char)((f + 1.f) * (7.f / 2.f))];
}

int main(void)
{
  float f;
  for (f = 0.f; f < (8.f * M_PI ); f += (M_PI / 8.f))
    putc(wav_to_char(sin(f)), stdout);
  putc('\n', stdout);
  return 0;
}