{"id":1614,"date":"2014-12-07T03:19:34","date_gmt":"2014-12-07T03:19:34","guid":{"rendered":"http:\/\/41j.com\/blog\/?p=1614"},"modified":"2014-12-07T03:19:34","modified_gmt":"2014-12-07T03:19:34","slug":"c-convert-tofrom-string","status":"publish","type":"post","link":"https:\/\/41j.com\/blog\/2014\/12\/c-convert-tofrom-string\/","title":{"rendered":"C++ convert to\/from string"},"content":{"rendered":"

One of the majority deficiencies in C++ has always been the lack of a simple standard method to convert to and from strings to numeric types. The C language extensions atoi<\/a> and itoa<\/a> are often available, but obviously only deal with integer types, and are non-standard. Cx11 appears to introduce these features in stoi and to_string methods.<\/p>\n

However, adapted from the C++ FAQ<\/a> this is the stringify.h header I’ve always used. It conveniently templatises the conversion (at least one example of templates not causing pain and suffering!). So you can convert a string to a double as: <\/p>\n

double d = convertTo<double>(mystring);<\/p>\n

Or convert a double to a string with:<\/p>\n

string s = stringify(d);<\/p>\n

#include <sstream>
\n#include <iostream>
\n#include <string>
\n#include <stdexcept><\/p>\n

#ifndef STRINGIFY_H
\n#define STRINGIFY_H<\/p>\n

class BadConversion : public std::runtime_error {
\npublic:
\n BadConversion(const std::string& s)
\n : std::runtime_error(s) {}
\n};<\/p>\n

template<class _type>
\ninline std::string stringify(_type x)
\n{
\n std::ostringstream o;
\n if (!(o << std::fixed << x))
\n throw BadConversion("stringify()");
\n return o.str();
\n}<\/p>\n

template<class _type>
\ninline _type convertTo(const std::string& s)
\n{
\n std::istringstream i(s);
\n _type x;
\n if (!(i >> x))
\n throw BadConversion("convertTo(\\"" + s + "\\")");
\n return x;
\n}<\/p>\n

#endif<\/p>\n","protected":false},"excerpt":{"rendered":"

One of the majority deficiencies in C++ has always been the lack of a simple standard method to convert to and from strings to numeric types. The C language extensions atoi and itoa are often available, but obviously only deal with integer types, and are non-standard. Cx11 appears to introduce these features in stoi and […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[1],"tags":[],"class_list":["post-1614","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_shortlink":"https:\/\/wp.me\/p1RRoU-q2","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/1614","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/comments?post=1614"}],"version-history":[{"count":1,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/1614\/revisions"}],"predecessor-version":[{"id":1615,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/posts\/1614\/revisions\/1615"}],"wp:attachment":[{"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/media?parent=1614"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/categories?post=1614"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/41j.com\/blog\/wp-json\/wp\/v2\/tags?post=1614"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}