ungetc()函数ungetc

ungetc()函数ungetc
语法:

1 2	?? #include <stdio.h> ?? int ungetc( int ch, FILE *stream );

函数ungetc()把字符ch放回到stream(流)中.

#include <stdio.h>

#include <ctype.h>

int main(void)

{

int ch;

int result = 0;

printf( "Enter an integer: " );

/* Read in and convert number: */

while( ((ch = getchar()) != EOF) && isdigit( ch ) )

result = result * 10 + ch - '0'; /* Use digit. */

if( ch != EOF )

ungetc( ch, stdin ); /* Put nondigit back. */

printf( "Number = %d\nNextcharacter in stream = '%c'", result, getchar() );

}

//输出结果

Output

Enter an integer: 521a

Number = 521Nextcharacter in stream = 'a'

Output

Enter an integer: 521

umber = 521Nextcharacter in stream = ''