关于Basic程序解释器及编译原理的简单化(1)---Basic器的语法分析及主要代码

关于Basic程序解释器及编译原理的简单化(1)---Basic器的语法分析及主要代码(9)         get_token();
        if (*token != ',')  serror(1);
        get_token();
    }
    else printf ("? ");  /* otherwise, prompt with / */
    var = toupper(*token) - 'A';  /* get the input var */

    scanf ("%d",&i);  /* read input */
    variables[var] = i;  /* store it */
}

/* execute a GOSUB command */
void gosub()
{
    char *loc;

    get_token();
    /* find the label to call */
    loc = find_label(token);
    if (loc=='\0')
        serror(7);  /* label not defined */
    else  {
        gpush(prog);  /* save place to return to */
        prog = loc;  /* start program running at that loc */
    }
}

/* return from GOSUB */
void greturn()
{
    prog = gpop();
}

/* GOSUB stack push function */
void gpush(char *s)
{
    gtos++;

    if (gtos==SUB_NEST)  {
        serror(12);
        return;
    }

    gstack[gtos] = s;
}

/* GOSUB stack pop function */
char *gpop()
{
    if (gtos==0)  {
        serror(13);
        return 0;
    }
    return gstack[gtos--];
}

main (int argc,char *argv[])
{
    char in[80];
    int answer;
    char *p_buf;