How can I split a long string in source code into several lines for more readability in C++?

Question

In other word how to make my code working if I don't want to write it one line?

#include <string>
using namespace std;

int main()
{
    string menu = "";
    menu += "MENU:\n"
        + "1. option 1\n"
        + "2. option 2\n"
        + "3. option 3\n"
        + "4. 10 more options\n";
}

"1. option 1\n" underlined red, and when I hover it it says expression must have integral or uscoped enum type. — Denys_newbie, Apr 12 '20 at 23:31

Brian61354270 · Accepted Answer · 2020-04-12T23:38:10.093

Simply remove the +'s:

#include <string>

int main()
{
    std::string menu = "MENU:\n"
        "1. option 1\n"
        "2. option 2\n"
        "3. option 3\n"
        "4. 10 more options\n";
}

Adjacent string literals are automatically concatenated by the compiler.

Alternatively, in C++11, you can use raw string literals, which preserve all indentation and newlines:

#include <string>

int main()
{
    std::string menu = R"(MENU:
1. option 1
2. option 2
3. option 3
4. 10 more options
)";

}

Ted Lyngmo · Answer 2 · 2020-04-12T23:30:44.543

2

You don't need the +s. By just leaving those out, the compiler will concatenate all the string literals into one long string:

menu += "MENU:\n"
    "1. option 1\n"
    "2. option 2\n"
    "3. option 3\n"
    "4. 10 more options\n";

edited Apr 12 '20 at 23:30

answered Apr 12 '20 at 23:25

Ted Lyngmo

93,841
5
60
108

To clarify, the compiler will concatenate any two consecutive strings, e.g. `"a" "b"` into `"ab"`. – IlCapitano Apr 12 '20 at 23:28
@IlCapitano Reworded a bit – Ted Lyngmo Apr 12 '20 at 23:30

score 1 · Answer 3 · answered Apr 12 '20 at 23:36

1

Just remove the add operators in your example. Consecutive strings with nothing between them are simply concatenated. So, for example, the two consecutive tokens "hello " "world" is the same as "hello world". But keep in mind that source code line breaks can separate any two tokens, so "hello " and "world" can be on separate lines, just as you wish.

answered Apr 12 '20 at 23:36

Larry Ruane

137
6

may be you omitted 'not' particle after word 'can' in last sentance? – Denys_newbie Apr 12 '20 at 23:53
@Denis_newbie — no, the last sentence is correct. They can be on separate lines. – Pete Becker Apr 13 '20 at 02:27

How can I split a long string in source code into several lines for more readability in C++?

3 Answers3