单选题 下面程序的功能是统计字串sub在母串s中出现的次数.请选择填空. #include "stdio.h" #include "string.h" main() { char s[80], sub[80]; int n; gets(s); gets(sub); printf("%d\n", count(s,sub)); } int count( char *p, char *q) { int m, n, k, num=0; for (m=0; p[m]; m++) for (【1】,k=0; q[k]==p[n]; k++, n++) if(q[【2】]=='\0') { num++; break;} return (num); }