# display symbols between numbers from a vector

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Vincent TORRELLI on 18 Oct 2019
Commented: Vincent TORRELLI on 18 Oct 2019
Hello,
I'm writing a code to help people on mental computation. To do so, I want to display a sum with the symbol "+" between two numbers located in a vector.
I know it should be simple but I did not succeed so far. Here is an example:
I want to display on command window:
>> 10 + 11
The values 10 and 11 are located in a vector such as:
calc=[10 11];
I tried to do the following code but it doesn't work:
sum_1= [calc(1)," + ", calc(2)];
disp(sum_1);
Can you help me please. Thank you very much.
Vincent

#### 1 Comment

darova on 18 Oct 2019
You should convert number into string
Use num2str

Ted Shultz on 18 Oct 2019
you can use fprintf to print just about anything you want.
calc=[10 11];
fprintf('%i + %i\n', calc(1), calc(2))

Show 1 older comment
Vincent TORRELLI on 18 Oct 2019
Thank you very much Ted !
One last thing:
For clarity purpose, I would like to have a space between the number and the symbol like the example:
1 + 3 - 4 - 5
Do you think it's feasible with your method ?
Vincent
Ted Shultz on 18 Oct 2019
If you want spaces, you may want to just build up the line element by element. One way to do this would be:
a=[ 1 3 -4 5 -10];
workingString = sprintf('%i ',a(1));
for ii = 2:numel(a)
if a(ii) >= 0
thisSymbol = '+';
else
thisSymbol = '-';
end
workingString = [workingString sprintf('%s %i ',thisSymbol , abs(a(ii) ))]; %#ok<AGROW>
end
workingString = [workingString newline];
disp(workingString)
this gives:
1 + 3 - 4 + 5 - 10
Vincent TORRELLI on 18 Oct 2019
Awesome, that's perfectly working.
Thank you very much !
Vincent

Steven Lord on 18 Oct 2019
Since you're using double quotes to create a string, turn your numeric vector into a string array then join the elements of that string array together.
calc = [10 11]
S = string(calc)
sum_1 = join(S, " + ")
You could do this in one line if you don't want to name the string temporary variable.
calc = [10 11]
sum_1 = join(string(calc), " + ")
Alternately if your calc vector is longer and you want to add different symbols you can use + to concatenate the string and numeric data together.
calc = 10:12;
sum1 = calc(1) + " + " + calc(2) + " * " + calc(3)
If this needs to run on an older release of MATLAB that doesn't support string, you can use sprintf.
calc = [10 11]
sum_1 = sprintf('%d + %d', calc)

Vincent TORRELLI on 18 Oct 2019
calc = [10 11]
S = string(calc)
sum_1 = join(S, " + ")
Indeed, the calc vector is parameterized so that its size can vary from 1 to n.
The calc vector contains "n" random numbers that can be either positive and negative.
The final goal will be to not print a "+" sign if the number is negative:
what I don't want: -15 + -16 + 13
what I want: -15 -16 +13
Do you know how to do it?