c 基础学习

////  main.c//  cc////  Created by cclyy on 14-7-14.//  Copyright (c) 2014年 cclyy. All rights reserved.//#include <stdio.h>#include <fcntl.h>#include <stdlib.h>#include <unistd.h>#include <sys/types.h>#include <sys/stat.h>#include "string.h"//结构体//typedef struct _ren//{//    int year;//    int month;//    int day;//    int sex;//    //    char name[16];//    char idcard[18];//}Ren;//////typedef struct _ren Ren;struct _Word{    char word[64];    int tpye; //0 名词, 1 动词        struct _Word *ptNext;};typedef struct _Word Word;int main (){//    Word ws[10];//    //    ws[0].tpye = 1;//    strcpy(ws[0].word, "abc");//    //    ws[1].tpye = 0;//    strcpy(ws[1].word, "abc");    Word *pWord = NULL;        pWord = (Word *)malloc(sizeof(Word));    pWord->tpye = 0;    strcpy(pWord->word, "test\0");        pWord->ptNext = NULL;            Word *pWord2 = NULL;        pWord2 = (Word *)malloc(sizeof(Word));    pWord2->tpye = 1;    strcpy(pWord2->word, "xxx\0");    pWord2->ptNext = NULL;        pWord->ptNext = pWord2;            printf("Hello, World!\n");    //    int a = 123;//    int b = (int)&a;//    int c = (int)&b;//    int d = (int)&c;//    //    int e = *(&d);//    //    //指针//    int * f = &c;//    //    printf("a=%d, b=%d, c=%d, d=%d, e=%d, f=%d\n", a, b, c, d, e, (int)f);//    //    char c_a = 'A';//    char * c_b = &c_a;//    //    char c_c = *c_b;//    //    printf("%c, %c\n", c_a, c_c);//    //    char * c_1 = "ABCD\0EFG";//    printf("%s\n", c_1);//    //    printf("+4=%s\n", c_1 + 4);//    printf("+5=%s\n", c_1 + 5);//    //    printf("len=%d\n", (int)strlen(c_1));//    printf("sizeof=%d\n", (int)sizeof(c_1));//    //    int i = 0;//    while(i++ < 9)//    {//       // printf("===>[%d][%s]\n", (int)c_1, c_1);//        c_1++;//    }////        //    打开文件        //int fd = open ( "/Users/cclyy/Desktop/c/cc/cc/123.txt" , O_RDONLY);    //printf("%d\n" , fd);    //char buffer[6] = {0};    //int rd = read (fd , buffer , 5 );    //printf("%d,%s\n" , rd ,buffer );            //打开文件并读取文件    //    int n=1;//    int fd = open ( "/Users/cclyy/Desktop/c/cc/cc/123.txt" , O_RDONLY);//    char buffer[6] = {0};//    while (n!=0)//    {//        char buffer[6] = {0};//        int rd=read(fd, buffer, 5);//        n = rd;//        printf("%s"  ,buffer );//    }//    //    close(fd);    //    创建文件//    int n=0;//    int fd =creat("/Users/cclyy/Desktop/c/cc/cc/456.txt", 0765);//    for (n=0 ; n<15; n++)//    {//        char buffer[4]={0};//        sprintf(buffer, "%d\n",n);//        printf("%d", n);//        write(fd, buffer, strlen(buffer));//    }//    //    close(fd);//    更该文件属性//    chmod("/Users/cclyy/Desktop/c/cc/cc/456.txt",0777);//        //    //    int fd = open("/Users/cclyy/Desktop/c/cc/cc/1.txt", O_RDONLY);//    int n = 0;//    char *A = "abc";//    char buffer[1024] = {0};//    while (1)//    {//        int rd = read(fd, buffer , 3);//        if (rd == 0)//        {//            break;//        }//        if (buffer == A)//        {//            n++;//        }//        //       //    }//    printf("%d" , n);//    //        //    strstr 查找字符串//    int fd = open("/Users/cclyy/Desktop/c/cc/cc/1.txt", O_RDONLY);//    int n = 0;//    char *A = "bcdef";//    char buffer[1024] = {0};//    int rd = read(fd, buffer, 1024);//    char *xxx = buffer;//    while (1)//    {//        char* st=strstr(xxx, A);//        if (st==NULL) {//            break;//        }//        n++;//        xxx=st+1;//    }//    //    printf("%d", n);//    //    结构体//    struct _ren xxx;//    Ren yyy;//    yyy.year = 1991;//    yyy.month = 11;//    yyy.day = 3;//    yyy.sex = 0;//    strcpy(yyy.name, "jcw");//    strcpy();        //    //    FILE* fp = fopen("/Users/cclyy/Desktop/c/cc/cc/1.txt", "r");//    char buffer[1024]={0};////    while (1) {//        char *fg = fgets(buffer, 1024, fp);//        //        printf("[%d]", feof(fp));//        if (fg == NULL) {//            break;//        }//        //        printf("[%s]",buffer);////    }//    fclose(fp);//    //    printf("%d", (int)sizeof(Ren));        //    malloc 申请固定内存    //    char buf[6 * 1024 * 1024] = { 0 };//    printf("[%s]", buf);//    //    char *bigbuf = malloc(10 * 1024 * 1024);//    printf("[%s]", bigbuf);//    //    //    free(bigbuf);//        //    int fd = open("/Users/cclyy/Desktop/c/cc/cc/1.txt", O_RDONLY);//    int ls = lseek(fd, 0, SEEK_END);//    char *buffer = malloc(ls);//    lseek(fd, 0, SEEK_SET);//    int rd = read(fd, buffer, ls);//    printf("%d\n%d\n" , ls , rd);//    printf("%s" , buffer);//    free(buffer);                                    return 0;}