C語言函數原型fgets fputs

fputs

int fputs ( const char * str, FILE * stream );

Write string to stream

Writes the string pointed by str to the stream.
The function begins copying from the address specified (str) until it reaches the terminating null character ('/0'). This final null-character is not copied to the stream.

 

Parameters

str

An array containing the null-terminated sequence of characters to be written.

stream

Pointer to a FILE object that identifies the stream where the string is to be written.

 

Return Value

On success, a non-negative value is returned.
On error, the function returns EOF.

 

Example

 

#include <stdio.h> int main () { FILE * pFile; char sentence [256]; printf ("Enter sentence to append: "); fgets (sentence,255,stdin); pFile = fopen ("mylog.txt","a"); fputs (sentence,pFile); fclose (pFile); return 0; }

 

This program allows to append a line to a file called mylog.txt each time it is run.

fgets 

 

char * fgets ( char * str, int num, FILE * stream );

<cstdio>

 

Get string from stream

Reads characters from stream and stores them as a C string into str until (num-1) characters have been read or either a newline or a the End-of-File is reached, whichever comes first.
A newline character makes fgets stop reading, but it is considered a valid character and therefore it is included in the string copied to str.
A null character is automatically appended in str after the characters read to signal the end of the C string.

 

Parameters

str

Pointer to an array of chars where the string read is stored.

num

Maximum number of characters to be read (including the final null-character). Usually, the length of the array passed as str is used.

stream

Pointer to a FILE object that identifies the stream where characters are read from.
To read from the standard input, stdin can be used for this parameter.

 

Return Value

On success, the function returns the same str parameter.
If the End-of-File is encountered and no characters have been read, the contents of str remain unchanged and a null pointer is returned.
If an error occurs, a null pointer is returned.
Use either ferror or feof to check whether an error happened or the End-of-File was reached.

 

Example

 

#include <stdio.h> int main() { FILE * pFile; char mystring [100]; pFile = fopen ("myfile.txt" , "r"); if (pFile == NULL) perror ("Error opening file"); else { fgets (mystring , 100 , pFile); puts (mystring); fclose (pFile); } return 0; }

 

This example reads the first line of myfile.txt or the first 100 characters, whichever comes first, and prints them on the screen.