sine_print_with_comments.c

/* In order to compile this on my linux system
 * even though the instructions were given like this
 * $ gcc sine_print.c -o sine_print
 * I had to add -lm or it will return exception
 * sine_print.c:(.text+0x8c): undefined reference to `sin'
 * collect2: ld returned 1 exit status
 * for some reason it wouldn't link the math.h at the compile step
 * So I typed $ gcc sine_print.c -lm -o sine_print
 * latter I saw a post with a similar problem and they typed
 * $ gcc -Wall foo.c -o foo -lm
 * I'm not sure if the syntax is a convention but the first way
 * worked for me. -Wall I have seen when compiling stuff in Linux but need to
 * look at the manpage still so check out those flags before you type it

 * Also another weird thing is when I typed
 * gcc sine_print.c -o sine_print.c
 * the file disappeared completely from my computer
 * is this a bug or normal behavior? IDK

 * prints a sideways sine wave in ASCII chars
*/

#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] = ' ';
    }
}