Error use of undeclared identifier itoa

• Forum
• Beginners
• How to convert data type int to char?

How to convert data type int to char?

1
2
3
4
5
6
7
8
9
10

#include <stdlib.h>

int main()
{
	int a(100);
	char buffer[4];
	itoa(a, &buffer[0], 10);

	return 0;
}

 In function 'int main()': 7:24: error: 'itoa' was not declared in this scope

1
2
3
4
5
6
7
8
9
10
11

#include <iostream>
#include <cstdlib> // now using C++ header

int main()
{
    int value = 100;
    char buffer[32] = ""; // plenty of space (and zero init)
    itoa(value, buffer, 10); // no actual need to take address of first elem
    std::cout << buffer << "n";
    return 0;
}

1
2
3
4
5
6
7
8
9
10
11
12

#include <iostream>
#include <sstream>
#include <string>

int main()
{
    int value = 100;
    std::ostringstream oss;
    oss << value;
    std::cout << oss.str() << "n";
    return 0;
}

Topic archived. No new replies allowed.

Hello,

Let’s take iostream.h for example. Our objective is to narrow out all *.h header files.

Typically if you use depreciated headers, e.g. iostream.h instead of iostream, you do not need the directive. This is because compilers that support depreciated headers for backward compatibility declare the «

using namespace std;» directive prior to including the ANSI header. However this mechanism is supported for backward compatibility, and you should avoid relying upon it in new code.

Keep in mind iostream is part of the C++ standard, iostream.h isn’t. iostream is somewhat more restrictive than the older iostream.h. One would possibly avoid problems by careful use of namespaces, but it would be a lot smarter to stick with one or the other.

You should avoid using the *.h version as much as possible, because some implementations have bugs in their *.h version. Moreover, some of them support non-standard code that is not portable, and fail to support some of the standard code of the STL.

Furthermore, the *.h version puts everything in the global namespace. The extension-less version is more stable and it’s more portable. It also places everything in the std namespace.

iostream.h is an old style method of including std C++ headers, and in opposite to iostream you don’t have to declare that you’re using the std namespace.

For example the string class which needs string, rather than string.h is a C header, and is not the same. It is equivilent to cstring which should be used instead.

In VC++ 6 iostream.h works, which is different than iostream. The *.h version was assembled before there was a standard for C++.

P.S. This pertains to most, if not all, *.h header files.

—

Stack Overflow

Segmentation Fault: I am an error in which a running program attempts to access memory not allocated to it and core dumps with a segmentation violation error. This is often caused by improper usage of pointers, attempts to access a non-existent or read-only physical memory address, re-use of memory if freed within the same scope, de-referencing a null pointer, or (in C) inadvertently using a non-pointer variable as a pointer.

Recommended Answers

All 5 Replies

#define _CRT_SECURE_NO_DEPRECATE
#define _CRT_NONSTDC_NO_DEPRECATE

#include <......> etc

Reply to this topic

В Visual C++ компилятор ругается:

А компилятор C++ Builder — проходит без ошибок.

Добавлено через 1 минуту и 12 секунд
Что не нравится компилятору Visual C++ ?  

———————

Web Sep 12, 2011 itoa () is not part of any standard so you shouldn’t use it. There’s better ways, i.e… C: int main () { char n_str [10]; int n = 25; sprintf (n_str, «%d», n); return 0; } …
From stackoverflow.com
Reviews 2

Web Dec 10, 2012 To use itoa () function, you need to include stdlib.h file, then you will not see the error while using itoa (). Share Improve this answer Follow answered Dec 10, 2012 …
From stackoverflow.com
Reviews 4

Web Dec 17, 2007 _itoa_s () is a non-standard function. It could be that your compiler doesn’t support it. Kai001 Author 122 December 15, 2007 11:51 PM I’m using VC 6.0. I thought …
From gamedev.net

Web String functions like strcpy,strcat,itoa…shows warning as «declared deprecated» in Visual Studio 8.0 instead it suggests to use functions which are enhanced secure versions of …
From daniweb.com

Web 13 use of undeclared identifiers errors, problem with the scope of variables. So I am getting some errors and I don’t know why because I already defined those functions in this …
From reddit.com

Web To declare a variable one must write its type followed by its name (also known as identifier). Once you’ve declared it, only then you are allowed to use it in expressions or …
From cs50.stackexchange.com

Web Jul 13, 2015 ajh32’s code above does not compile on C++ Shell (including either <stdlib.h> or <cstdlib>) In function ‘int main ()’: 7:24: error: ‘itoa’ was not declared in this scope But …
From cplusplus.com

Web May 30, 2022 std::iota — cppreference.com std:: iota C++ Algorithm library Fills the range [first, last) with sequentially increasing values, starting with value and repetitively …
From en.cppreference.com

Web ‘itoa’ : function does not take 1 arguments & ‘c’ : undeclared identifierHelpful? Please use the *Thanks* button above! Or, thank me via Patreon: https://www…
From youtube.com

Web The function itoa () is not part of standard C or C++. If using C, you can use sprintf; if using C++, you can use an ostringstream. C++ Example: Example 1: Using ostringstream …
From cboard.cprogramming.com

Web Aug 22, 2022 itoa () is not supported on all UNix platforms natively. Example above by rstaveley is good to do this function,. I always use the following — #include <iostream> …
From experts-exchange.com

Web Nov 9, 2012 itoa is a non-standard function which is supported by some compilers. Going by the error, it’s not supported by your compiler. Your best bet is to use snprintf () …
From stackoverflow.com

Web The word identifier is used for the names we give to our variable. This type of error deals with the cases where we make some mistakes while dealing with the identifiers i.e, this …
From codespeedy.com

Web itoa char * itoa ( int value, char * str, int base ); Convert integer to string (non-standard function) Converts an integer value to a null-terminated string using the specified base …
From cplusplus.com

Web Apr 5, 2019 prog.c: In function ‘main’: prog.c:5:18: error: ‘x’ undeclared (first use in this function) printf(«%d», x); ^ prog.c:5:18: note: each undeclared identifier is reported only …
From geeksforgeeks.org

Web Oct 1, 2018 $ bundle install Warning: the running version of Bundler (1.16.2) is older than the version that created the lockfile (1.16.3). We suggest you upgrade to the latest …
From github.com

Web Jan 9, 2017 Pull requests Projects Insights New issue make error: use of undeclared identifier ‘iota’ #1 Closed cn0xroot opened this issue on Jan 9, 2017 · 2 comments on …
From github.com