字符串处理常用函数

#include <iostream>
using namespace std;

int main()
{
    char message1[]="Original message";
    strcpy(message1,"different");//different0essage0
    cout<<message1<<endl;//different

    char message2[]="Original message";
//    strcpy(message2,"A different message");//运行时错误 所以要复制的字符串要小于等于目的数组长度
    cout<<message2<<endl;

    char *p1="abc";
    char *p2="abcd";
    cout<<strcmp(p1,p2)<<endl;//-1

    char p3[]="abc";
    char p4[]="abcde";
    strncpy(p3,p4,3);
    cout<<p3<<endl;
    strncpy(p3,p4,4);//当源字符串长度大于目的字符串时，只有sizeof(dst)个会赋值到目的数组中，且不会以''结尾
    cout<<p3<<endl;
    p3[3]='';
    cout<<p3<<endl;
    
}

void main()
{
    cout<<lookup_keyword("while",keyword,5)<<endl;
    char buff[10]="zhangwen";
    char buff2[10]={'0'};
    
    memcpy(buff2,buff,5);//复制buff的前5个元素到buff2
    cout<<buff2<<endl;//zhang
    
    memset(buff,'a',3);//将buff的前三个内存位置的值设置为'a'
    cout<<buff<<endl;//aaangwen
    
    cout<<memcmp(buff,buff2,3)<<endl;//a<z所以打印-1
    
    char *p=(char*)memchr(buff,'n',10);//查找buff中是否有字符‘n’有则返回指针 无则返回NULL
    cout<<*p<<endl;//打印出n

}