【C】從檔案中讀取數字

標籤：

假設src.txt是包含各種ascii字元的文字檔。請提取src.txt文本中的數字，並儲存在dst.txt檔案中。數字之間用空格隔開。

 1 #include <stdio.h> 2 #include <stdlib.h> 3 #include <string.h> 4  5 #define IN 0 6 #define OUT 1 7  8 /*從名為src檔案中找到數字，將其寫入到名字為dst的檔案中*/ 9 int write_digit(char *dst, char *src)10 {11     FILE *fp1;12     FILE *fp2;13     if( !(fp1 = fopen(src,"r")))14     {15         fprintf(stderr,"failed to open %s\n",src);16         exit(-1);17     }18     if( !(fp2 = fopen(dst,"w+")))19     {20         fprintf(stderr,"failed to open %s\n",dst);21         exit(-1);22     }23     int ch;24     int state = OUT;25     while( (ch = fgetc(fp1))!=EOF)26     {27         if( ch < ‘0‘ || ch > ‘9‘)28         {29             if(IN == state)30             {31                 fputc(‘ ‘,fp2);32             }33             state = OUT;34         }35         else 36         {37             fputc(ch,fp2);38             state = IN;39         }40     }41     fclose(fp1);42     fclose(fp2);43     return 0;44 }45 46 int main()47 {48     char *s1 = "src.txt";49     char *s2 = "dst.txt";50     write_digit(s2, s1);51     return 0;  52 }

 

【C】從檔案中讀取數字