在字符串S1中去除所有字符串S2

/* 自学C语言第一个自己写的小程序，起因是把书上题看错了……*/
#include 
int strlen(char s[]);
void squeeze(char s1[], char s2[]);

main(){
	char s1[] = "i am your father, father's fatheer.";
	char s2[] = "father";
	squeeze(s1, s2);
	for (int i = 0; s1[i] != '\0'; ++i)
		putchar(s1[i]);
	system("pause");
	return 0;
}

void squeeze(char s1[], char s2[]) {
	int i, j, u;
	j = u = 0;
	int l = strlen(s2);
	for (i = 0; s1[i] != '\0'; i++) {
		if (s1[i] != s2[u]) {
			if (u != 0) {
				for (int x = 0; x <= u; ++x) {
					s1[j] = s1[i - u + x];
					++j;
				}
				u = 0;
			}
			else
				s1[j++] = s1[i];
		}
		else {
			if (u < (l-1))
				++u;
			else
				u = 0;
		}
	}
	s1[j] = '\0';
}


int strlen(char s[]) {
	int i;
	for (i = 0; s[i] != '\0'; i++)
		;
	return i;
}