c语言写一个接口函数判断集合A是否属于集合B

好的，这个问题属于技术问题，我可以回答。您需要编写一个函数，可以判断集合A是否是集合B的子集。下面是一个示例代码：

#include <stdio.h>

int isSubset(int A[], int B[], int m, int n) 
{ 
    int i = 0, j = 0; 
    for (i = 0; i < n; i++) 
    { 
        for (j = 0; j < m; j++) 
        { 
           if(B[i] == A[j]) 
              break; 
        } 
          
        /* If the above inner loop was
        not broken at all then arr2[i]
        is not present in arr1[] */
        if (j == m) 
           return 0; 
    } 
      
    /* If we reach here then all
    elements of arr2[] are present
    in arr1[] */
    return 1; 
} 

int main() 
{ 
    int A[] = {11, 1, 13, 21, 3, 7}; 
    int B[] = {11, 3, 7, 1}; 
    
    int m = sizeof(A)/sizeof(A[0]); 
    int n = sizeof(B)/sizeof(B[0]); 
  
    if(isSubset(A, B, m, n)) 
      printf("A is a subset of B\n"); 
    else
      printf("A is not a subset of B\n");   
} 

您可以将集合A和集合B的元素作为数组传入isSubset函数中，并根据返回值判断集合A是否是集合B的子集。