编写c语言程序在数组pai a[52]={{1,'a'},{1,'b'}........} 中随意抽出20张牌，放在数组int b[20]={........}中，单独排序，编一个函数程序来完成这项任务。

以下是一个C语言的示例程序，可以完成你的要求：

#include <stdio.h>
#include <stdlib.h>
#include <time.h>

struct Card {
    int number;
    char suit;
};

void shuffle(struct Card* deck, int size) {
    srand(time(NULL));
    for (int i = 0; i < size; i++) {
        int j = rand() % size;
        struct Card temp = deck[i];
        deck[i] = deck[j];
        deck[j] = temp;
    }
}

int cmp(const void* a, const void* b) {
    struct Card* card_a = (struct Card*)a;
    struct Card* card_b = (struct Card*)b;
    return card_a->number - card_b->number;
}

void sort_cards(struct Card* hand, int size) {
    qsort(hand, size, sizeof(struct Card), cmp);
}

int main() {
    struct Card deck[52] = {
        {1, 'a'}, {1, 'b'}, {1, 'c'}, {1, 'd'},
        {2, 'a'}, {2, 'b'}, {2, 'c'}, {2, 'd'},
        {3, 'a'}, {3, 'b'}, {3, 'c'}, {3, 'd'},
        {4, 'a'}, {4, 'b'}, {4, 'c'}, {4, 'd'},
        {5, 'a'}, {5, 'b'}, {5, 'c'}, {5, 'd'},
        {6, 'a'}, {6, 'b'}, {6, 'c'}, {6, 'd'},
        {7, 'a'}, {7, 'b'}, {7, 'c'}, {7, 'd'},
        {8, 'a'}, {8, 'b'}, {8, 'c'}, {8, 'd'},
        {9, 'a'}, {9, 'b'}, {9, 'c'}, {9, 'd'},
        {10, 'a'}, {10, 'b'}, {10, 'c'}, {10, 'd'},
        {11, 'a'}, {11, 'b'}, {11, 'c'}, {11, 'd'},
        {12, 'a'}, {12, 'b'}, {12, 'c'}, {12, 'd'},
        {13, 'a'}, {13, 'b'}, {13, 'c'}, {13, 'd'}
    };

    shuffle(deck, 52);

    int b[20] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19};
    struct Card hand[20];
    for (int i = 0; i < 20; i++) {
        hand[i] = deck[b[i]];
    }

    sort_cards(hand, 20);

    for (int i = 0; i < 20; i++) {
        printf("%d%c ", hand[i].number, hand[i].suit);
    }
    printf("\n");

    return 0;
}

程序首先定义了一个结构体 `Card`，表示一张牌，包括一个数字和一个花色。然后定义了一个 `shuffle` 函数，用于打乱牌组。之后定义了一个 `cmp` 函数，用于排序时比较两张牌的大小。最后定义了 `sort_cards` 函数，用于对手中的牌进行排序。

在 `main` 函数中，首先调用 `shuffle` 函数打乱牌组，然后定义了一个数组 `b`，表示要抽出的牌在牌组中的索引。接着通过循环将抽出的牌存入 `hand` 数组中，最后调用 `sort_cards` 函数对 `hand` 数组进行排序。最后输出排序后的牌。