Как из float сделать string c

Как из float сделать string c

Write a C function ftoa() that converts a given floating-point number or a double to a string. Use of standard library functions for direct conversion is not allowed. The following is prototype of ftoa(). The article provides insight of conversion of C double to string.

Example:

• ftoa(1.555, str, 2) should store “1.55” in res.
• ftoa(1.555, str, 0) should store “1” in res.

We strongly recommend to minimize the browser and try this yourself first. A simple way is to use sprintf(), but use of standard library functions for direct conversion is not allowed. Approach: The idea is to separate integral and fractional parts and convert them to strings separately. Following are the detailed steps.

Convert float to string in C++ (3 Ways)

In this article, we will learn about three different ways to convert a float to a string in C++ i.e.

1. Using std::to_string() function
2. Using std::stingstream
3. Using Boost’s lexical_cast() function.

Let’s discuss them one by one.

Convert float to string using to_string()

C++ provides a function std::to_string() for data type conversion. We can use this to convert a float to a string. For example,

We passed a float value to the to_string() function, and it converted the given float to a string and returned the string object. It will keep the precision level as it is. If you want more control over the precision level of float while converting it to string, then look at the following technique using stringstream.

Convert float to string with specified precision using stringstream in C++

C++ provides a class stringstream, which provides a stream-like functionality. We can insert different types of elements in stringstream and get a final string object from the stream. We can use that to convert float to string. In the stream, we can also set the precision level of float-type elements before conversion. Check out this example,

Output:

Read More:

In the stringstream, we inserted a float to the stringstream, and then the stream converted the float to string. Also, as we set the precision level to 3, it rounded off the value to keep only three digits after the dot.

Convert float to string using boost::lexical_cast()

The C++ boost library, provides a template function for data type conversion. It helps to convert elements from one data type to another. We can use that to convert a float to string. For example,

Output:

Summary:

We learned about three different ways to convert a float value to a string in C++.

Related posts:

Advertisements

Thanks for reading.

Leave a Comment Cancel Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.

Advertisements

Advertisements

Advertisements

Advertisements

C++ – Smart Pointers

C++ Threads

C++ – STL Tutorials

Terms of Use

Disclaimer

Copyright © 2023 thisPointer

To provide the best experiences, we and our partners use technologies like cookies to store and/or access device information. Consenting to these technologies will allow us and our partners to process personal data such as browsing behavior or unique IDs on this site. Not consenting or withdrawing consent, may adversely affect certain features and functions.

Click below to consent to the above or make granular choices. Your choices will be applied to this site only. You can change your settings at any time, including withdrawing your consent, by using the toggles on the Cookie Policy, or by clicking on the manage consent button at the bottom of the screen.

Как из float сделать string c

This forum has migrated to Microsoft Q&A. Visit Microsoft Q&A to post new questions.

• ProfileText
• Sign in

Answered by:

Question

Answers

I’m sure there’s a simpler way to do this, but right now this is the best I can come up with. As someone already said, atof() will take care of your string to float conversions, however there is no ftoa() for float to string, so you need to come up with a different way to do things.

I can think of several ways to tackle this, but I’m sure there must be an easier way to do it. I just can’t think of it right now. You could use the sprintf function to print data (In this case your float number) into a string. An example would be:

char str[20] = «»; float f = 4.5; sprintf(str, «%f», f);

That way you would be printing the data contained in your float number into the string. Bad thing about this is that you could overrun the buffer which results in nasty run-time errors. You could opt for using the secure sprintf_s version, but that requires you know beforehand the number of characters to write. You could also use string streams, like in the following example:

This last one is pretty useful when you are doing several conversions, because you’re practically creating an additional buffer. Once you have your output in that buffer, you can get the string contained in it with the str() function.

Преобразование числа с плавающей запятой в строку в C++

Программирование и разработка

В этой статье мы узнаем, как мы можем преобразовать число с плавающей запятой в строку на C++, используя различные методы:

• Использование to_string()
• Использование строкового потока
• Использование макросов
• Использование lexical_cast из библиотеки boost

1. Использование to_string()

Метод to_string() принимает одну целочисленную переменную или другой тип данных и преобразует ее в строку.

Синтаксис:

Пример:

С++

Объяснение: Функция to_string преобразует заданное значение с плавающей запятой в строку.

2. Использование строкового потока

Строковый поток связывает строковый объект с потоком, позволяя вам читать из строки, как если бы это был поток (например, cin). Чтобы использовать stringstream, нам нужно подключить заголовочный файл sstream. Класс stringstream чрезвычайно полезен при разборе входных данных. Основные методы: