c - fprintf(textFilepointer) 在文件中打印两次

Question

#include "aservelibs/aservelib.h"
#include <stdio.h>
#include <math.h>

FILE *textFilePointer;

int main()
{
    int counter = 0;
    int note;

    printf("Press key on Axiom MIDI keyboard to display note number\n");


    textFilePointer = fopen("/Users/jonnymaguire/Documents/Uni Work/Audio Programming /iap/iapProj/Builds/MacOSX/build/Debug/textp15.txt", "w");

    do
    {
        if(textFilePointer == NULL)
        {
            printf("!Error Opening File!");
        }
        else
        {
            /*get frequency from user*/

            note = aserveGetNote();

            fprintf(textFilePointer, "note = %d\n", note);
            fprintf(textFilePointer, "hex note = %x\n\n", note);
            counter++;


        }

    }
    while(counter < 16);

    fclose(textFilePointer);

    return 0;               /*end*/
}

这个程序只是简单地将音符编号打印到文件中，一旦它们被用户在键盘上弹奏。然而，它打印所有东西的两倍，所以我不能记录 15 个不同的音符编号和十六进制音符编号，因为它每次都写双倍。为什么？

Answer 1

如果您在播放每个音符时收到两条消息，一条是按键，一条是按键释放，您可以通过将音符消息打印到控制台来判断这一点，而不是的到一个文件。试试这个:

#include "aservelibs/aservelib.h"
#include <stdio.h>
#include <math.h>

int main(void) { 
    int counter = 0;
    int note;
    printf("Press key on Axiom MIDI keyboard to display note number\n");
    do
    {
        /*get frequency from user*/
        note = aserveGetNote();
        printf("note = %d\n", note);
        counter++;
    }
    while(counter < 16);
    return 0;
}