c语言----程序记录

1.结构体写入文件，读取

#include <stdio.h>
#include <string.h>
#include <stdlib.h> 
#define max 5

struct books{
    char title[20];
    char author[20];
    int price;
};

const char * fileName="books.txt";
int size=sizeof(struct books);

void read(struct books bks[]);
void write(struct books bks[]);
void list(struct books bks[]);
void demo(struct books bks[]);

void main(void)
{
    struct books bks[max];
    
    //write(bks);
    read(bks);

}


void write(struct books bks[])
{
    FILE * fp;
    int i=0;
    int addList;
    if((fp=fopen(fileName,"a+b")) == NULL)
    {
        printf("file open fail"); 
    }
    
    puts("大侠，你想添加几条数据?");
    scanf("%d",&addList);
    
    if(addList>0)
    {
        do{
            printf("please add new book title
");
            scanf("%s",&bks[i].title);
            printf("please add new book author
");
            scanf("%s",&bks[i].author);
            printf("please add new book price
");
            scanf("%d",&bks[i].price);
            i++;
            fwrite(&bks[i],size,1,fp);
        }while(i<addList);
    }
                    
}

void read(struct books bks[])
{
    FILE * fp;
    int i=0;
    if((fp=fopen(fileName,"r+")) == NULL)
    {
        printf("file open fail"); 
    }
    
    rewind(fp);
    
    while( i<max && fread(&bks[i],size,1,fp) == 1)
    {
        printf("title is %s,author is %s,price is %d
",bks[i].title,bks[i].author,bks[i].price);
        i++;
    }
        
}

 2. 获取指定字符在字符串的最后的位置

  

#include <string.h>
#include <stdio.h>
#include <stdlib.h>

int main(int argc,char *argv[])
{
    if(argc<2)
    {
        puts("params error");
        exit(1);
    }
     
   char *p;
   char c = argv[2][0];  //传入来的都是字符串，得到需要的字符 ，去掉最后的 
   int weizhi;
   
   p = strrchr(argv[1],c);//得到字符c在字符串argv[1]中的地址，返回的是字符指针 
   
   if(p)
     weizhi = p - argv[1];  //两个指针相减，得到位置距离 
        printf("%d",weizhi);
   else
     puts("not found");   
   
   return 0;
}

3.字符串查找

#include <string.h>
#include <stdio.h>
#include <stdlib.h>
#define TRUE   1
#define FALSE  0 
#define ERROR  0

int strStart(char *,char *);

int main(int argc,char *argv[])
{
     char message[]="hello,welcome to China"; 
     char find[]="Ch";
     int start = strStart(message,find);
     printf("%d",start);
}

int strStart(char * String,char * find)
{
    int start=-1,i=0,j=0;
    
    //得到字符串长度 
    int StringLen = strlen(String);
    int findLen   = strlen(find);
    //判断是否为空
    if(StringLen<=0 || findLen<=0)
    {
        return FALSE;
    }
    //判断子串的长度是否大于母串的长度
    if(StringLen < findLen)
    {
        return FALSE;
    } 
    //开始查找 
    for(i=0;i<=StringLen;i++)
    {
        if(String[i]==find[j])
        {
            if(start<0)
                start = i;
            
            j++;    
        }else{
            if(j<findLen)
                start=-1;
        }
    }
    return start;
}