字符串

//============================================================================
// Name        : C++Study.cpp
// Author      : pan
// Version     :
// Copyright   : Your copyright notice
// Description : Hello World in C++, Ansi-style
//============================================================================


#include <stdio.h>
#include <cstdlib>
#include <iostream>
#include <queue>
#include <stack>
#include <assert.h>
#include <string.h>
using namespace std;


struct String {


char* s = NULL;
int length = 0;


};
void assignString(String* dst, const char* t) {


assert(t!=NULL);
if (dst->s) {
delete dst->s;
}
int len = strlen(t);
dst->s = new char[len + 1];
dst->s[len] = '\0'; ///////这里好好理解下
for (int i = 0; i < len; i++) {
dst->s[i] = t[i];
dst->length++;
}


}
String* concatString(String* s1, String* s2) {


String* s = new String;
s->s = new char[s1->length + s2->length + 1];
s->s[s1->length + s2->length] = '\0';
int i = 0;
while (s1->s[i] != '\0') {
s->s[i] = s1->s[i];
i++;
}
while (s2->s[i] != '\0') {
s->s[i] = s2->s[i];
i++;
}
s1->s = new char[s1->length + s2->length + 1];
i = 0;
while (s->s[i] != '\0') {
s1->s[i] = s->s[i];
cout << s->s[i];
i++;
}
s1->s[i] = '\0';
delete s->s;
delete s;
return s1;
}


void showString(String* s) {
int i = 0;
while (s->s[i] != '\0') {
cout << s->s[i];
i++;
}
}


int indexSubString(String* src, String* sub) { //求子串的位置
int i = 0, j = 0;
while (i < src->length && j < sub->length) {
if (src->s[i] == sub->s[j]) {
i++;
j++;
} else {
i = i - j + 1;
j = 0;
}
}
if (j == sub->length)
return i - j + 1;


return 0;
}
int main() {


/* if('\0'==NULL)
{
cout<<"yes";
}*/
String s1, s2;
char* c = "abcdefg";
assignString(&s1, c);
assignString(&s2, c);
String* s = concatString(&s1, &s2);
showString(s);


delete s1.s;
delete s2.s;
delete s->s;


return 0;
}