display symbols between numbers from a vector

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

[darova]

You should convert number into string

Use num2str

Answer 1

[Ted Shultz]

you can use fprintf to print just about anything you want.

calc=[10 11];
fprintf('%i + %i\n', calc(1), calc(2))

[Ted Shultz]

If you want to print +/- based on sign, and you have a lot of values, you could use:

a=[ 1 3 -4 5]

fprintf('%i',a(1))
fprintf('%+i',a(2:end))

this gives:

1+3-4+5

[Vincent TORRELLI]

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 ?

Thank you in advance.

Vincent

[Ted Shultz]

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]

Awesome, that's perfectly working.

Thank you very much !

Vincent

Answer 2

[Steven Lord]

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)

Answer 3

[Vincent TORRELLI]

Thank you every body for your answers.

Steven Lord, your following answer fits very well with my problem:

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?

Thank you in advance.

Vincent