Alternative to Itoa() For Converting Integer to String C++

Alternative to itoa() for converting integer to string C++?

In C++11 you can use std::to_string:

#include <string>

std::string s = std::to_string(5);

If you're working with prior to C++11, you could use C++ streams:

#include <sstream>

int i = 5;
std::string s;
std::stringstream out;
out << i;
s = out.str();

Taken from http://notfaq.wordpress.com/2006/08/30/c-convert-int-to-string/

Converting int to string in C

Use snprintf, it is more portable than itoa.

itoa is not part of standard C, nor is it part of standard C++; but, a lot of compilers and associated libraries support it.

Example of sprintf

char* buffer = ... allocate a buffer ...
int value = 4564;
sprintf(buffer, "%d", value);

Example of snprintf

char buffer[10];
int value = 234452;
snprintf(buffer, 10, "%d", value);

Both functions are similar to fprintf, but output is written into an array rather than to a stream. The difference between sprintf and snprintf is that snprintf guarantees no buffer overrun by writing up to a maximum number of characters that can be stored in the buffer.

Want to Convert Integer to String without itoa function

I found solution regarding this..

I am Happy to and i want which i expected.

#include <string.h>
#include <stdlib.h>

char *i_to_a(int num);

int main()
{

    char *str = i_to_a(4567);
    printf("%s",str);
    free(str);
    str = NULL;
return 0;

}
int no_of_digits(int num)
{
    int digit_count = 0;

    while(num > 0)
    {
        digit_count++;
        num /= 10;
    }

    return digit_count;
}


char *i_to_a(int num)
{
    char *str;
    int digit_count = 0;

    if(num < 0)
    {
        num = -1*num;
        digit_count++;
    }

    digit_count += no_of_digits(num);   
    str = malloc(sizeof(char)*(digit_count+1));

    str[digit_count] = '\0';

    while(num > 0)
    {
        str[digit_count-1] = num%10 + '0';
        num = num/10;
        digit_count--;
    }

    if(digit_count == 1)
        str[0] = '-';

    return str;
}

C++ standard alternative to itoa() to convert int to base 10 char*

I recommend using roybatty's answer, but I think sprintf should work too. I think when you used it you forgot the format string. It should be:

char buf[16];
std::snprintf(buf, sizeof(buf), "%d", integer);

Easiest way to convert int to string in C++

C++11 introduces std::stoi (and variants for each numeric type) and std::to_string, the counterparts of the C atoi and itoa but expressed in term of std::string.

#include <string> 

std::string s = std::to_string(42);

is therefore the shortest way I can think of. You can even omit naming the type, using the auto keyword:

auto s = std::to_string(42);

Note: see [string.conversions] (21.5 in n3242)

Converting integer to string in C without sprintf

You can use itoa where available. If it is not available on your platform, the following implementation may be of interest:

https://web.archive.org/web/20130722203238/https://www.student.cs.uwaterloo.ca/~cs350/common/os161-src-html/atoi_8c-source.html

Usage:

char *numberAsString = itoa(integerValue); 

UPDATE

Based on the R..'s comments, it may be worth modifying an existing itoa implementation to accept a result buffer from the caller, rather than having itoa allocate and return a buffer.

Such an implementation should accept both a buffer and the length of the buffer, taking care not to write past the end of the caller-provided buffer.

Purpose of char a[0] in converting integer to string using itoa()

Since itoa function is non-standard, this is a discussion of a popular signature itoa(int, char*, int).

Second parameter represents a buffer into which a null-terminated string representing the value is copied. It must provide enough space for the entire string: in your case, that is "123", which takes four characters. Your code passes a[] as the buffer, but the size of a[] is insufficient to accommodate the entire "123" string. Hence, the call causes undefined behavior.

You need to make a large enough to fit the destination string. Passing a buffer of size 12 is sufficient to accommodate the longest decimal number that can be produced by itoa on a 32-bit system (i.e. -2147483648). Replace char a[0] with char a[12] in the declaration.

converting integer to string C++

Besides I would prefer if I could convert the same int to char array.

char *charPtr = new char[ s.length() + 1 ] ; // s is the string in the snippet posted
strcpy( charPtr, s.c_str() ) ;

// .......

delete[] charPtr ; // Should do this, else memory leak.

integer to string conversion using itoa()

You have to use

char string[5];
int integer= 10;
snprintf(string, 5,"%d",integer);

Because itoa is not part of the standard function which is supported by some compilers..

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