模拟std::vector

---

---

vector.size()

unsigned len=0; //len初始化

vector.push_back(value_type)

void push(char val){str[len++]=val;str[len]='\0';}

vector.pop()

void pop{if(len)len--;} //if(len)避免越界

整体：

#include<stdio.h>
char str[110]="\0";
unsigned len=0;
void push(char val){str[len++]=val;str[len]='\0';}
void pop(){if(len)len--;}
int main(){
    while(1){
        char c=getchar();
        if(c==EOF)break;
        if(c=='@')pop();
        else push(c);
    }
    printf("%s",str);
}