以编程方式在Linux上查找可用的声卡

这是示例代码;用gcc -o countcards countcards.c -lasound编译它：

#include <alsa/asoundlib.h>
#include <stdio.h>

int main()
{
    int totalCards = 0;   // No cards found yet
    int cardNum = -1;     // Start with first card
    int err;

    for (;;) {
        // Get next sound card's card number.
        if ((err = snd_card_next(&cardNum)) < 0) {
            fprintf(stderr,"Can't get the next card number: %sn",snd_strerror(err));
            break;
        }

        if (cardNum < 0)
            // No more cards
            break;

        ++totalCards;   // Another card found,so bump the count
    }

    printf("ALSA found %i card(s)n",totalCards);

    // ALSA allocates some memory to load its config file when we call
    // snd_card_next. Now that we're done getting the info,tell ALSA
    // to unload the info and release the memory.
    snd_config_update_free_global();
}

这是从cardnames.c减少的代码(也打开每张卡以读取其名称).