请大佬们帮我康康这到底是怎么回事，小白刚开始学，不太懂。。。
p1++; if (p2 == ‘/0’) return p1 - len2; else return NULL; } }} return 0;}char findFirst(char* sourceStr, char* subStr){ char* p1 = sourceStr, * p2 = subStr; int len1 = 0, len2 = 0; while (*p1 != ‘/0’) { len1++; p1++; } while (*p2 != ‘/0’) { len2++; p2++; } p1 = sourceStr; p2 = subStr; if (len1 < len2) { return NULL; } else { while (p1 != ‘/0’ && p2 != ‘/0’) { if (p1 == p2) p2++; else p2 = subStr;#include
#define NULL 0;
using namespace std;
char findFirst(char sourceStr, char subStr);
int main()
{
char str[30], substr[20];
char p; p = str;
cout << “请输入源串” << endl;
cin >> str;
cout << “请输入子串” << endl;
cin >> substr;
p = findFirst(str, substr);