strcspn函数与basic_istream::gcount 函数

size_t strcspn ( const char * str1, const char * str2 );

Get span until character in string

Scans str1 for the first occurrence of any of the characters that are part of str2, returning the number of characters of str1 read before this first occurrence.

The search includes the terminating null-characters, so the function will return the length of str1 if none of the characters of str2 are found in str1.

Parameters

str1

C string to be scanned.

str2

C string containing the characters to match.

 

Return value

The length of the initial part of str1 not containing any of the characters that are part of str2.
This is the length of str1 if none of the characters in str2 are found in str1.

 1 /* strcspn example */
 2 #include <stdio.h>
 3 #include <string.h>
 4 
 5 int main ()
 6 {
 7   char str[] = "fcba73";
 8   char keys[] = "1234567890";
 9   int i;
10   i = strcspn (str,keys);
11   printf ("The first number in str is at position %d.\n",i+1);
12   return 0;
13 }

Output:

The first number in str is at position 5

 

 

 

basic_istream::gcount 

Returns the number of characters read during the last unformatted input. 

 

streamsize gcount( ) const;

Return Value

The extraction count.

Remarks

Useto read unformatted characters. 

 1 // basic_istream_gcount.cpp
 2 // compile with: /EHsc
 3 #include <iostream>
 4 using namespace std;
 5 
 6 int main( ) 
 7 {
 8    cout << "Type the letter 'a': ";
 9 
10    ws( cin );
11    char c[10];
12 
13    cin.get( &c[0],9 );
14    cout << c << endl;
15 
16    cout << cin.gcount( ) << endl;
17 }

Type the letter 'a': a 1