C++/php/python/shell program reads files by line or console

Writing programs often need to read information by line from a file or standard input, summarized here. Easy to use

1. C + +

Read file

1#include <stdio.h>2#include <string.h>3 4 intMain () {5     Const Char* In_file ="Input_file_name";6     Const Char* Out_file ="Output_file_name";7 8FILE *p_in = fopen (In_file,"R");9     if(!p_in) {Tenprintf"Open file%s failed!!!", in_file); One         return-1; A     } -          -FILE *p_out = fopen (Out_file,"W"); the     if(!p_in) { -printf"Open file%s failed!!!", out_file); -         if(!p_in) { - fclose (p_in); +         } -         return-1; +     } A  at     Charbuf[2048]; -     //read file contents by line -      while(Fgets (BUF,sizeof(BUF), p_in)! =NULL) { -         //Write to File -Fwrite (BUF,sizeof(Char), strlen (BUF), p_out); -     } in  - fclose (p_in); to fclose (p_out); +     return 0; -}

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Reading standard input

1#include <stdio.h>2 3 intMain () {4     Charbuf[2048];5 6 gets (BUF);7printf"%s\n", buf);8 9     return 0;Ten } One  A ///scanf encounters a space and other characters will end - ///gets encounters line break end

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2. Php

Read file

1<?PHP2 $filename= "Input_file_name";3 4 $fp=fopen($filename, "R");5 if(!$fp){6     EchoThe Open File$filenamefailed\n ";7     Exit(1);8 }9 Else{Ten      while(!feof($fp)){ One         //fgets (file,length) does not specify a length of 1024 bytes by default A         $buf=fgets($fp); -  -         $buf=Trim($buf); the         if(Empty($buf)){ -             Continue; -         } -         Else{ +             Echo $buf." \ n "; -         } +     } A     fclose($fp); at } -?>

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Reading standard input

1<?PHP2 $fp=fopen("/dev/stdin", "R");3 4  while($input=fgets($fp, 10000)){5         $input=Trim($input);6        Echo $input." \ n ";7 }8 9 fclose($fp);Ten?>

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3. Python

Reading standard input

1 #Coding=utf-82 3 #If you want to write Chinese in the Python2 py file, you must add a line to declare the file encoded comments, otherwise python2 will use ASCII encoding by default. 4 #coding statement, written in the first line is good5 ImportSYS6 7input =Sys.stdin8 9  forIinchInput:Ten     #I represents the current input line One  Ai =I.strip () -     PrintI -  theInput.close ()

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4. Shell

Read file

1 #!/bin/bash23 #读取文件, use the file name directly; To read the console, use/dev/stdin45 while the readline6do7      echo  ${line}8 done < filename

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Reading standard input

1 #!/bin/bash23 while readline4do5      echo  ${line}6 Done </dev/stdin

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C++/php/python/shell program reads files by line or console