在没有sstream c ++的情况下从字符串中提取整数

Question

What is the simplest way to extract the following integers from a string such as: "54 232 65 12".

And what if the last number is a long long int. Is it possible to do this without sstream

Answer 1

Try this:

#include <cstdlib>
#include <cstdio>
#include <cerrno>
#include <cstring>

int main()
{
    char str[] = " 2 365  2344 1234444444444444444444567 43";

    for (char * e = str; *e != '\0'; )
    {
        errno = 0;
        char const * s = e;
        unsigned long int n = strtoul(s, &e, 0);

        if (errno)                       // conversion error (e.g. overflow)
        {
            std::printf("Error (%s) encountered converting:%.*s.\n",
                        std::strerror(errno), e - s, s);
            continue;
        }

        if (e == s) { ++e; continue; }   // skip inconvertible chars

        s = e;

        printf("We read: %lu\n", n);
    }
}

In C++11 you can also use std::strtoull , which returns an unsigned long long int .

( Live example .)