c字符-字符串问题集锦

存储int,char,uchar没区别，只有提取的时候有区别

#include "stdio.h"

main () {
        unsigned char u=127;
        unsigned char u0=48;
        char c=127;
        char c0=48;
        int i=127;
        int i0=48;
        printf("u=%d;u0=%d;u=%c;u0=%c;bin=%x\n",u,u0,u,u0,u);
        printf("c=%d;c0=%d;c=%c;c0=%c;bin=%x\n",c,c0,c,c0,c);
        printf("i=%d;i0=%d;i=%c;i0=%c;bin=%x\n",i,i0,i,i0,i);
}

c中字符和字符串是两种性质完全不同的类型

如strcmp 参数只能用string类型

fgets read one line with automatic adding \0

---

 char flag[] = "WROTE"; 
 strncpy(shm_addr, flag, strlen(flag)); 
        向p, copy string len is 5.
strncpy(shm_addr + strlen(flag), buff, strlen(buff));  
从p+5开始copy，copy buff length
strncmp(shm_addr, flag, strlen(flag))
string比较，比较的string的len，是从shm_addr 到strlen(flag)