C language——to Replace a specified Line in a Text File—V2

[root@localhost 桌面]# gedit tmp.c

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				// C Language to Replace a specified Line in a Text File

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

				//filename: "/etc/hosts"
				//str: "mpe.localhost"
				//return the matched line number
				int findline(char *filename, char *str)
				{
				    // open the file for reading
				    FILE *file = fopen(filename, "r");

				    // make sure the file opened properly
				    if(NULL == file)
				    {
				        fprintf(stderr, "Cannot open file: %s
", filename);
				        return 1;
				    }

				    // set up the buffer to read the line into. Don't worry too much
				    // if some of the lines are longer than 80 characters - the buffer
				    // will be made bigger if need be.
				    size_t buffer_size = 80;
				    char *buffer = malloc(buffer_size * sizeof(char));

				    // read each line and print it to the screen
				    int line_number = 0, find = 0;
				    while(-1 != getline(&buffer, &buffer_size, file))
				    {
				        line_number++;
				        if(NULL != strstr(buffer, str))
				        {
				            find = 1;
				            break;
				        }
				        //printf("%d: %s", line_number, buffer);
				    }

				    if(find == 0) line_number = 0;

				    fclose(file);
				    free(buffer);

				    return line_number;
				}

				void replaceline(char *filename, int delete_line, char *newcontent)
				{
				    FILE *fileptr1, *fileptr2;
				    //char filename[40];
				    char c;
				    int temp = 1;

				    fileptr1 = fopen(filename, "r");
				    //print the contents of file .
				    while ((c = getc(fileptr1)) != EOF)
				    {
				        printf("%c", c);
				    }

				    //take fileptr1 to start point.
				    rewind(fileptr1);
				    //open tempinterm.txt in write mode
				    fileptr2 = fopen("tempinterm.txt", "w");

				    while ((c = getc(fileptr1)) != EOF)
				    {
				        //till the line to be deleted comes,copy the content to other
				        if (temp != delete_line) {
				            putc(c, fileptr2);
				            while ((c = getc(fileptr1)) != 'n') putc(c, fileptr2);
				            putc('n', fileptr2);
				            temp++;
				        } else {
				            while ((c = getc(fileptr1)) != 'n');    //read and skip the line
				            //while ((c = getchar()) != 'n') putc(c, fileptr2);
				            while(*newcontent != '0') putc(*newcontent++, fileptr2);
				            putc('n', fileptr2);
				            temp++;
				        }
				    }

				    //append a new line at the end of file
				    if(delete_line == 0)
				    {
				        while(*newcontent != '0') putc(*newcontent++, fileptr2);
				        putc('n', fileptr2);
				    }

				    fclose(fileptr1);
				    fclose(fileptr2);
				    remove(filename);
				    rename("tempinterm.txt", filename);
				}

				int main(void)
				{
				    FILE *fileptr1;
				    char c;

				    char filename[6] = "hosts";

				    int line = findline(filename, "mpe.localhost");
				    replaceline(filename, line, "10.108.162.227   mpe.localhost");

				    fileptr1 = fopen(filename, "r");
				    //reads the character from file
				    //until last character of file is encountered
				    while ((c = getc(fileptr1)) != EOF) printf("%c", c);
				    fclose(fileptr1);
				    return 0;
				}

[root@localhost 桌面]# gcc tmp.c -o tmp
[root@localhost 桌面]# ./tmp
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
127.0.0.1   localhost localhost.localdomain localhost4 localhost4.localdomain4
::1         localhost localhost.localdomain localhost6 localhost6.localdomain6
10.108.162.227   mpe.localhost
[root@localhost 桌面]#

<script>window._bd_share_config={"common":{"bdSnsKey":{},"bdText":"","bdMini":"2","bdMiniList":false,"bdPic":"","bdStyle":"0","bdSize":"16"},"share":{}};with(document)0[(getElementsByTagName('head')[0]||body).appendChild(createElement('script')).src='http://bdimg.share.baidu.com/static/api/js/share.js?v=89860593.js?cdnversion='+~(-new Date()/36e5)];</script>

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