文件操作_练习_0305

#Makefile

#如果每个.c文件中都含有main函数，使用Makefile，可直接生成与之对应的可执行文件，不需要生成中间过程文件

src = $(wildcard *.c)
targets = $(patsubst %.c, %, $(src))

CC = gcc
CFLAGS = -Wall -g

all:$(targets)
$(targets):%:%.c
    $(CC) $(CFLAGS) $< -o $@
clean:
    rm $(targets)
.PHONY:clean

//fgets_fputs_cp.c

#include <stdio.h>

void cp(int argc, char *argv[])
{
    FILE *srcp, *destp;
    char buff[1024];

    if(argc != 3)
        printf("Usage: cp src_file dest_file\n");

    srcp = fopen(argv[1], "r");
    destp = fopen(argv[2], "w");

    if(srcp == NULL || destp == NULL)
    {
        printf("open file failure!\n");
    }

    while((fgets(buff, sizeof(buff), srcp)) != NULL)
        fputs(buff, destp);

    fclose(srcp);
    fclose(destp);
}

int main(int argc, char *argv[])
{
    cp(argc, argv);
    return 0;
}

//cat.c

//实现cat指令功能，注意不要用>，系统自动捕捉，导致功能不能实现

#include <stdio.h>

void cat(int argc, char **argv)
{
   FILE *fp;
   char buff[1024];

   printf("cat\n");

   if(argc == 2)
   {
        printf("argc = 2\n");
        fp = fopen(argv[argc - 1], "r");
        if(fp == NULL)
            printf("open file failure!\n");
        while((fgets(buff, sizeof(buff), fp)) != NULL)
            fputs(buff, stdout);
        fclose(fp);
   }
   if(argc == 3)
   {
        printf("argc = 3\n");
        int ch;

        fp = fopen(argv[argc - 1], "a");
        if(fp == NULL)
            printf("open file failure!\n");

        while((ch = fgetc(stdin)) != EOF)
            fputc(ch, fp);
        fclose(fp);
   }

}


int main(int argc, char *argv[])
{
    cat(argc, argv);

    return 0;
}

//error.c

//错误输出的简单实现

#include <stdio.h>
#include <errno.h>

void myerror(void)
{
    FILE *fp;
    fp = fopen("1.c", "r");
    perror("no such file:");

}

int main(int argc, const char *argv[])
{
    myerror();
    return 0;
}

//error_sys.c

//系统错误输出的简单实现

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

#define MAXLINE     80

void err_sys(const char *fmt,...)
{
        int err = errno;
        char buf[MAXLINE+1];
        va_list ap;
        va_start(ap, fmt);

        vsnprintf(buf, MAXLINE, fmt, ap);
        snprintf(buf+strlen(buf), MAXLINE-strlen(buf), " : %s", strerror(err));
        strcat(buf, "\n");
        fputs(buf, stderr);

        va_end(ap);
        exit(1);
}

int main(int argc, char *argv[])
{
        FILE *fp;
        if(argc != 2)
        {
                fputs("Usage: ./a.out pathname\n", stderr);
                exit(1);
        }
        fp = fopen(argv[1], "r");
        if(fp == NULL)
        {
                err_sys("%s():%d - Open file %s", __func__, __LINE__, argv[1]);
        }
        printf("Open %s OK\n", argv[1]);
        fclose(fp);
        return 0;

}

//log.c

//自定义的日志文件的简单实现

#include <stdio.h>
#include <time.h>

void mylog(char *str)
{
   time_t t;
   struct tm *tm_str;
   FILE *fp;

   t = time(NULL);
   tm_str = localtime(&t);

   fp = fopen("log.txt","a");
   if(fp == NULL)
        printf("open file failure\n");

   fprintf(fp, "%d-%d-%d %d:%d%d :%s\n", (tm_str->tm_year)+1900,tm_str->tm_mon+1,tm_str->tm_mday,tm_str->tm_hour,tm_str->tm_min,tm_str->tm_sec, str);

   printf("%d-%d-%d %d:%d:%d :%s\n", tm_str->tm_year+1900,tm_str->tm_mon+1,tm_str->tm_mday,tm_str->tm_hour,tm_str->tm_min,tm_str->tm_sec, str);
}

int main(int argc, char *argv[])
{
    mylog("add a line");
    mylog("delete a line");
    return 0;
}

//student_manager.c

//简单学生管理系统的实现：
//增、删、改、查

#include <stdio.h>
#include <string.h>
int number = 3;
typedef struct student
{
    int id;
    char name[16];
    int math;
    int english;
    float avg;

    struct student *next;
}stud_t;


void init(stud_t *s, int num)
{
    int i;
    for (i = 0; i < num; i++)
    {
        printf("id name math english\n");
        scanf("%d %s %d %d",&s[i].id, s[i].name, &s[i].math, &s[i].english);
    }
}

void average(stud_t *s, int num)
{
    int i;
    for (i = 0; i < num; i++)
    {
        s[i].avg = ((float)(s[i].math + s[i].english))/2;
    }
}

void show(stud_t *s, int num)
{
    int i;
    printf("id name math english\n");
    for (i = 0; i < num; i++)
    {
        printf("%d\t%s\t%d\t%d\t%f\n", s[i].id, s[i].name, s[i].math, s[i].english, s[i].avg);
    }
}



void range(stud_t *s, int num)
{
    int i, j;
    for (i = 0; i < num - 1; i++)
    {
        for (j = i + 1; j < num; j++)
        {
            stud_t tmp;
            if((s[i].math + s[i].english) < (s[j].math + s[j].english))
            {
                tmp = s[i];
                s[i] = s[j];
                s[j] = tmp;
            }
        }
    }
}


void delete(stud_t *s, int num)
{
    int i = 0, j, del_num;

    printf("del_num = ");
    scanf("%d", &del_num);

    while(del_num != s[i].id && i < num)
        i++;
    if(i < num)
    {
        number--;
        for (j = i; j < num - 1; j++)
        {
            s[j] = s[j + 1];
        }
    }
    else
        printf("delete_num not exist\n");

}

void guide(void)
{
    printf("0:guide\n");
    printf("1:chioce\n");
    printf("2:init\n");
    printf("3:show\n");
    printf("4:delete\n");
    printf("5:range\n");
    printf("6:exit\n");
}

void choice(stud_t *s, int num)
{
    int n;
    guide();
    while(1)
    {
        printf("choose(0~6):");
        scanf("%d", &n);

        if(n == 6)
            break;
        switch(n)
        {
            case 0:guide();break;
            case 1:choice(s, num);break;
            case 2:
            {
                init(s, num);
                average(s, num);
                break;
            }
            case 3:show(s, num);break;
            case 4:
            {
                delete(s, num);
                num--;
                break;
            }
            case 5:range(s, num);break;
            default:;
        }
    }
}


int main(int argc, const char *argv[])
{
    stud_t s[number];
    choice(s, number);
    return 0;
}