C/C++ STL之 #include 頭文件

頭文件cstdio/stdio.h是C/C++使用最頻繁的文件，因為文件中包含很多常用的方法，如下所示：

<1> 文件操作

remove

#include <stdio.h>

int main ()
{
  if( remove( "myfile.txt" ) != 0 )
    perror( "Error deleting file" );
  else
    puts( "File successfully deleted" );
  return 0;
}

rename

#include <stdio.h>

int main ()
{
  int result;
  char oldname[] ="oldname.txt";
  char newname[] ="newname.txt";
  result= rename( oldname , newname );
  if ( result == 0 )
    puts ( "File successfully renamed" );
  else
    perror( "Error renaming file" );
  return 0;
}

<2> 文件訪問

fopen，fclose

#include <stdio.h>
int main ()
{
  FILE * pFile;
  pFile = fopen ("myfile.txt","w");
  if (pFile!=NULL)
  {
    fputs ("fopen example",pFile);
    fclose (pFile);
  }
  return 0;

<3> 格式化輸入/輸出

scanf，printf

#include <stdio.h>

int main ()
{
  char str [80];
  int i;

  printf ("Enter your family name: ");
  scanf ("%79s",str);  
  printf ("Enter your age: ");
  scanf ("%d",&i);
  printf ("Mr. %s , %d years old.\n",str,i);
  printf ("Enter a hexadecimal number: ");
  scanf ("%x",&i);
  printf ("You have entered %#x (%d).\n",i,i);
  
  return 0;
}

<4> 字符輸入/輸出

getc, putc: 對文件中內容操作，getc為獲取文件中一個字符，putc向文件寫入一個字符

getc

#include <stdio.h>
int main ()
{
  FILE * pFile;
  int c;
  int n = 0;
  pFile=fopen ("myfile.txt","r");
  if (pFile==NULL) perror ("Error opening file");
  else
  {
    do {
      c = getc (pFile);
      if (c == '$') n++;
    } while (c != EOF);
    fclose (pFile);
    printf ("File contains %d$.\n",n);
  }
  return 0;
}

putc

#include <stdio.h>

int main ()
{
  FILE * pFile;
  char c;

  pFile=fopen("alphabet.txt","wt");
  for (c = 'A' ; c <= 'Z' ; c++) {
    putc (c , pFile);
    }
  fclose (pFile);
  return 0;
}

getchar, putchar, gets, puts

getchar: 輸入一個字符，putchar：輸出一個字符，gets：輸入一個字符串，puts：輸出一個字符串

#include <stdio.h>

int main ()
{
  int c;
  puts ("Enter text. Include a dot ('.') in a sentence to exit:");
  do {
    c=getchar();
    putchar (c);
  } while (c != '.');
  return 0;
}