CODEWITHSUNDEEP
c++arraystype-conversion
GhostVaibhav
GhostVaibhav

Reputation: 120

Putting an integer into a character array in C++

As I have been looking on this topic for a lot of time on this site, I couldn't find a helpful solution to my problem. So here's my problem :

If I have any number, say num = 256, I want to save this number in a character array, say a[10], like :

a[0] = 2
a[1] = 5
a[2] = 6
Storing in their respective indices

also the num variable is not static and it's value is dynamically entered by the user on runtime. But the size of the character array will be static.

Upvotes: 0

Views: 374

Answers (3)

ΦXocę 웃 Пepeúpa ツ
ΦXocę 웃 Пepeúpa ツ

Reputation: 48258

a way is decomposing the number in hundred, tens and units... modulo can help and log10 will be useful too:

this is going to be a nice work around if you arent allowed to convert to string

here an example:

int value = 256;
int myArray[3];
auto m = static_cast<int>(ceil(log10(value)));
for(int i =0; i < m; ++i)
{
    myArray[m-1-i] = static_cast<int>(value/pow(10,i))%10;
}

Upvotes: 1

bitmask
bitmask

Reputation: 34628

You can convert an integral value to its decimal representation with std::to_string:

std::string const dec = std::to_string(num);

If you have a character array, say char a[4], you can copy the data there element-wise:

for (std::size_t i = 0; std::begin(a) + i < std::end(a) && i < dec.size(); ++i) {
  a[i] = dec[i] - '0';
}

Edit: See Konrad Rudolph's answer for a simpler (and presumably faster) way of doing this.

Upvotes: 2

Konrad Rudolph
Konrad Rudolph

Reputation: 545588

C++17 has std::to_chars for this purpose:

char a[10];

if (auto const result = std::to_chars(a, a + sizeof a - 1, 256); result.ec != std::errc()) {
    // An error occurred.
} else {
    *result.ptr = '\0';
}

Upvotes: 2

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