std::vscanf, std::vfscanf, std::vsscanf

Since C++11

Header: <cstdio>

Reads data from a variety of sources, interprets it according to format and stores the results into locations defined by vlist.

# Declarations

int vscanf( const char* format, std::va_list vlist );

(since C++11)

int vfscanf( std::FILE* stream, const char* format, std::va_list vlist );

(since C++11)

int vsscanf( const char* buffer, const char* format, std::va_list vlist );

(since C++11)

# Parameters

# Return value

Number of arguments successfully read, or EOF if failure occurs.

# Notes

All these functions invoke va_arg at least once, the value of arg is indeterminate after the return. These functions to not invoke va_end, and it must be done by the caller.

# Example

#include <cstdarg>
#include <cstdio>
#include <iostream>
#include <stdexcept>
 
void checked_sscanf(int count, const char* buf, const char *fmt, ...)
{
    std::va_list ap;
    va_start(ap, fmt);
    if (std::vsscanf(buf, fmt, ap) != count)
        throw std::runtime_error("parsing error");
    va_end(ap);
}
 
int main()
{
    try
    {
        int n, m;
        std::cout << "Parsing '1 2'... ";
        checked_sscanf(2, "1 2", "%d %d", &n, &m);
        std::cout << "success\n";
        std::cout << "Parsing '1 a'... ";
        checked_sscanf(2, "1 a", "%d %d", &n, &m);
        std::cout << "success\n";
    }
    catch (const std::exception& e)
    {
        std::cout << e.what() << '\n';
    }
}

# See also