• c程序设计语言_习题7-6_对比两个输入文本文件_输出它们不同的第一行_并且要记录行号


    Write a program to compare two files, printing the first line where they differ.

    Here's Rick's solution:

    /******************************************************
       KnR 7-6
       --------
       Write a program to compare two files and print the
       first line where they differ.
    
       Author: Rick Dearman
       email: rick@ricken.demon.co.uk
    
       Note: This program prints ALL the lines that are 
             different using the <> indicators used by
    	 the unix diff command. However this program
    	 will not cope with something as simple as a
    	 line being removed.
    	 
    	 In reality the program would be more useful
    	 if it searched forward for matching lines. 
    	 This would be a better indicator of the simple
    	 removal of some lines.
    	 
    	 This has lead me to track down a version of the 
    	 "diff" command available on GNU/Linux systems.
    	 for more information go to the web site at:
    	 www.gnu.org
    
    ******************************************************/
    #include <stdio.h>
    #include <string.h>
    #define MAXLINE 1000
    
    void diff_line( char *lineone, char *linetwo, int linenumber )
    {
      if(strcmp (lineone, linetwo) < 0 || strcmp (lineone, linetwo) > 0)
        printf( "%d<%s
    %d>%s
    ", linenumber, lineone, linenumber, linetwo);
    }
    
    int main(int argc, char *argv[] )
    {
      FILE *fp1, *fp2;
      char fp1_line[MAXLINE], fp2_line[MAXLINE];
      int i;
    
      if ( argc != 3 )
        {
          printf("differ fileone filetwo
    ");
          exit(0);
        }
    
      fp1 = fopen( argv[1], "r" );
      if ( ! fp1 )
        {
          printf("Error opening file %s
    ", argv[1]);
        }
    
      fp2 = fopen( argv[2], "r" );
      if ( ! fp2 )
        {
          printf("Error opening file %s
    ", argv[2]);
        }
      i = 0;
      while ( (fgets(fp1_line, MAXLINE, fp1) != NULL) 
          && (fgets(fp2_line, MAXLINE, fp2) != NULL))
      {
        diff_line( fp1_line, fp2_line, i );
        i++;
      }
    
      return 0;
    }

    and here's "flippant squirrel"'s solution:

    /* Exercise 7-6 - write a program to compare two files, printing the first line
     * where they differ
     *
     * Note : I amended this a bit...if a file is shorter than the other, but is identical
     * up to that point, the program prints out "EOF" as the string that's not equal. 
     * 
     */
     
    
    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    
    #define BUFF_SIZE 1000
    
    /* uses fgets, removes the '
    ' at the end of the string if it exists */
    char *safegets(char *buffer, int length, FILE *file)
    {
            char *ptr;
            int len;
            
            if (buffer != NULL)
            {
                    ptr = fgets(buffer, length, file);
                    
                    if (ptr != NULL)
                    {
                            len = strlen(buffer);
                    
                            if (len > 0)
                            {
                                    if (buffer[len - 1] == '
    ')
                                    {
                                            buffer[len - 1] = '';
                                    }
                            }
                    }
                    
                    return ptr;
            }       
            
            return NULL;
    }
    
    int main(int argc, char *argv[])
    {
            FILE *leftFile, *rightFile;
            char buff1[BUFF_SIZE], buff2[BUFF_SIZE];
            char *ptr1, *ptr2;
            unsigned long lineNum = 0;
            
            if (argc < 3)
            {
                    fprintf(stderr, "Usage : 7_6 <path to file> <path to file>
    ");
                    return 0;
            }
            
            if (!(leftFile = fopen(argv[1], "r")))
            {
                    fprintf(stderr, "Couldn't open %s for reading
    ", argv[1]);     
                    return 0;
            }
            
            if (!(rightFile = fopen(argv[2], "r")))
            {
                    fprintf(stderr, "Couldn't open %s for reading
    ", argv[2]);
                    fclose(leftFile); /* RJH 10 Jul 2000 */
                    return 0;
            }
            
            /* read through each file, line by line */
            ptr1 = safegets(buff1, BUFF_SIZE, leftFile);
            ptr2 = safegets(buff2, BUFF_SIZE, rightFile);
            ++lineNum;
            
            /* stop when either we've exhausted either file's data */
            while (ptr1 != NULL && ptr2 != NULL)
            {
                    /* compare the two lines */
                    if (strcmp(buff1, buff2) != 0)
                    {
                            printf("Difference:
    ");
                            printf("%lu	"%s" != "%s"
    ", lineNum, buff1, buff2);
                            goto CleanUp;
                    }
                    
                    ptr1 = safegets(buff1, BUFF_SIZE, leftFile);
                    ptr2 = safegets(buff2, BUFF_SIZE, rightFile);
                    ++lineNum;
            }       
    
            /* 
             * if one of the files ended prematurely, it definitely 
             * isn't equivalent to the other 
             */
            if (ptr1 != NULL && ptr2 == NULL)
            {
                    printf("Difference:
    ");
                    printf("%lu	"%s" != "EOF"
    ", lineNum, buff1);
            }       
            else if (ptr1 == NULL && ptr2 != NULL)
            {
                    printf("Difference:
    ");
                    printf("%lu	"EOF" != "%s"
    ", lineNum, buff2);
            }
            else
            {
                    printf("No differences
    ");
            }
    
    CleanUp:
    
            fclose(leftFile);
            fclose(rightFile);      
            return EXIT_SUCCESS;    
    }


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  • 原文地址:https://www.cnblogs.com/haore147/p/3648433.html
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