如何将String中指定位置的字符取出，删除

#include char *delete(char *p, int i);char a;int main(){char a[40], *b;int i;printf("请输入字符串\n");scanf("%s", a);printf("请输入你要删除第几个字符\n");scanf("%d", &i);b = delete( a, i);if(b == NULL){printf(" 删除失败\