type conversion - C++ integer from string -

how convert std::string unsigned integer, , allowing long inputs?

for example, input of 5000000000 should return 705032704 (5000000000 mod 2^32), assuming here unsigned 32 bits. input of 9999999999999999999999999999 should return 268435455.

std::stoi , friends give std::out_of_range when such large number provided.

using std::istringstream::operator>>(unsigned) fails given such input.

is there function convert string integer, without bailing out in case of large inputs? (i'd prefer avoid writing 1 myself if possible.)

you can write function yourself:

unsigned int get_uint(const std::string &s) {     unsigned int r = 0u;     for(auto c : s) {         assert(std::isdigit(c));         r = r * 10 + (c - '0');     }     return r; } 

live example

this works because unsigned overflow works modulo arithmetic in c++.

from 3.9.1/4

unsigned integers, declared unsigned, shall obey laws of arithmetic modulo 2^n n number of bits in value representation of particular size of integer