CODEWITHSUNDEEP
c++int
Srinath Mandava
Srinath Mandava

Reputation: 3462

How to print positive numbers with a prefix + in C++

Is there any way to print the integer along with its sign in c++...i.e. by default if the number is negative we would get a - sign printed. In the same way can we get + before the positive numbers.

int x=-1;
cout<<"x="<<x;

gives output x=-1

but,..

int x=+1;
cout<<"x="<<x;

gives output as x=1 but how do i get it printed as x=+1

I know we can take cases by using if-else for x>0 and x<0;..but without using the if-else is there any direct way of printing in c++

Upvotes: 5

Views: 6734

Answers (3)

Ciro Santilli OurBigBook.com
Ciro Santilli OurBigBook.com

Reputation: 383748

C++20 std::format option +

According to https://en.cppreference.com/w/cpp/utility/format/formatter#Standard_format_specification the following should hold:

#include <format>

// "1,+1,1, 1"
std::cout << std::format("{0:},{0:+},{0:-},{0: }", 1);

// "-1,-1,-1,-1"
std::cout << std::format("{0:},{0:+},{0:-},{0: }", -1);

The existing fmt library implements it for before it gets official support: https://github.com/fmtlib/fmt Install on Ubuntu 22.04:

sudo apt install libfmt-dev

Modify source to replace:

  • <format> with <fmt/core.h>
  • std::format to fmt::format

main.cpp

#include <iostream>

#include <fmt/core.h>

int main() {
    std::cout << fmt::format("{0:},{0:+},{0:-},{0: }\n", 1);
    std::cout << fmt::format("{0:},{0:+},{0:-},{0: }\n", -1);
}

and compile and run with:

g++ -std=c++11 -o main.out main.cpp -lfmt
./main.out

Output:

1,+1,1, 1
-1,-1,-1,-1

More information at: std::string formatting like sprintf

Upvotes: 1

galets
galets

Reputation: 18492

How about:

cout<<"x="<<(x>0)?"+":""<<x;

it's a bit clumsy, but fits the bill

Upvotes: -1

NPE
NPE

Reputation: 500683

Use std::showpos:

int x = 1;
std::cout << "x=" << std::showpos << x;

Upvotes: 14

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