Function for getting the ordinal of a number? - c++

Question

I was about to write a C++ function doing the following:
1 ---> "1st"
2 ---> "1nd"
3 ---> "3rd"
...
17657 --> "17657th"
...
i.e. produces the ordinal extension string for that number (it doesn't have to do an itoa() of the number itself). But then I thought "surely something in the standard library or boost does this already?"
Notes:
I know it's not hard to write this, there's an implementation in Python right here on SO, I just don't want to duplicate code.
I need this in English, obviously. A multi-language version would be nice for political-correctness considerations, not more than that...

Answer 1

Here's what I ended up writing:
const char* ordinal_suffix(int n)
{
static const char suffixes [][3] = {"th", "st", "nd", "rd"};
auto ord = n % 100;
if (ord / 10 == 1) { ord = 0; }
ord = ord % 10;
if (ord > 3) { ord = 0; }
return suffixes[ord];
}
The code golf solutions are cute, but - they really do optimize for terseness, not anything else. This is faster (although it could be made even faster by putting the suffixes in a .cpp out of the function body and making the code inlinable), much clearer, and still more terse than most other answers here.

Answer 2

// Returns numbers with ordinal suffix as string
// Based on https://stackoverflow.com/questions/3109978/display-numbers-with-ordinal-suffix-in-php
std::string NumberToOrdinal(size_t number) {
std::string suffix = "th";
if (number % 100 < 11 || number % 100 > 13) {
switch (number % 10) {
case 1:
suffix = "st";
break;
case 2:
suffix = "nd";
break;
case 3:
suffix = "rd";
break;
}
}
return std::to_string(number) + suffix;
}

Answer 3

I'm pretty sure you can adapt the four line solution at Display numbers with ordinal suffix in PHP. Unfortunately, I don't think there is such a thing in a common C++ lib.

Answer 4

try this...
#include <iostream>
using namespace std;
void suffix(int n, char suff[]);
// creates the ordinal suffix
// for a given number
int main()
{
char s[5];
int x;
cout << "Enter a number to find the ordinal suffix for ";
cin >> x;
suffix(52111,s);
}
void suffix(int n, char suff[])
{
if(n%100 == 11 || n%100 == 12 || n%100 == 13)
{
cout << "suffix is: " << n << "th";
cout << endl;
}
else
{
if(n%10 == 1)
{
cout << "Suffix is: " << n << "st";
cout << endl;
}
else
{
if(n%10 == 2)
{
cout << "Suffix is: " << n << "nd";
cout << endl;
}
else
{
if(n%10 == 3)
{
cout << "Suffix is: " << n << "rd";
cout << endl;
}
else
{
if(n%10 == 4 || n%10 == 5 || n%10 == 6 || n%10 == 7 || n%10 == 8 || n%10 == 9 || n%10 == 0)
{
cout << "Suffix is: " << n << "th";
cout << endl;
}
}
}
}
}
}

Answer 5

I used the following string function to accomplish it.
#include <string>
#include <iostream>
using namespace std;
string ordinal(int i)
{
if(i==1)
{
return "First";
}
if(i==2)
{
return "Second";
}
if(i==3)
{
return "Third";
}
if(i==4)
{
return "Fourth";
}
if(i==5)
{
return "Fifth";
}
if(i==6)
{
return "Sixth";
}
if(i==7)
{
return "Seventh";
}
if(i==8)
{
return "Eighth";
}
}
int main()
{
for(int i=0; i<8; i++)
{
cout << ordinal(i+1) << " number: ";
}
return 0;
}

Answer 6

#include <iostream>
#include <string>
std::string number_to_ordinal(int number)
{
// Convert number to string
std::string ordinal = std::to_string(number);
// Get the last character of the number to later determine ordinal indicator
char last_char = ordinal.back();
// Get the last two characters of the number to deal with ordinal indicator conditions
std::string last_two_char;
if(ordinal.size() > 1)
last_two_char = ordinal.substr(ordinal.size() - 2, ordinal.size());
// Determine ordinal indicator. Each number with a last character ending in '1', '2',
// and '3' require ordinal indicators of 'st', 'nd', and 'rd', respectively. However,
// numbers with the last two characters ending in '11', '12', and '13' require 'th'
// as the ordinal indicator.
if(last_two_char != "11" && last_char == '1')
ordinal += "st";
else if (last_two_char != "12" && last_char == '2')
ordinal += "nd";
else if (last_two_char != "13" && last_char == '3')
ordinal +="rd";
else
ordinal += "th"; // All other numbers require 'th' as the ordinal indicator
return ordinal;
}
///////////////////////////////////////////////////////////////////////
// Main Program
///////////////////////////////////////////////////////////////////////
int main()
{
// Test number to ordinal
for(int i = 17657; i < 17725; i++)
std::cout << number_to_ordinal(i) << std::endl;
return 0;
}