Converting between types in MATLAB - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of converting numeric array to logical

What is the output of this MATLAB code?

a = [0 1 2 -3 0];
b = logical(a);
disp(b);

MATLAB

a = [0 1 2 -3 0];
b = logical(a);
disp(b);

A [0 0 0 0 0]

B [false true true true false]

C [false 1 1 1 false]

D [0 1 1 1 0]

💡 Hint

Logical conversion treats zero as false and nonzero as true.

In MATLAB, logical conversion changes zeros to false and any nonzero number to true. Displaying a logical array shows 'false' and 'true'.

❓ Predict Output

intermediate

Result of char to double conversion

What is the output of this MATLAB code?

c = 'MATLAB';
d = double(c);
disp(d);

MATLAB

c = 'MATLAB';
d = double(c);
disp(d);

A [77 65 84 76 65 66]

B ['M' 'A' 'T' 'L' 'A' 'B']

C [109 97 116 108 97 98]

D [0 0 0 0 0 0]

💡 Hint

double converts characters to their ASCII numeric codes.

The double function converts each character to its ASCII code. 'M' is 77, 'A' is 65, etc.

❓ Predict Output

advanced

Output of converting numeric to string and back

What is the value of variable y after running this MATLAB code?

x = 123.45;
s = string(x);
y = double(s);

MATLAB

x = 123.45;
s = string(x);
y = double(s);

A NaN

B Error: Cannot convert string to double directly

C [49 50 51 46 52 53]

D 123.45

💡 Hint

double applied to a string array returns NaN if string is not numeric array.

The string '123.45' cannot be directly converted to a numeric double array by double(). Instead, double(string) returns NaN. To convert string to number, use str2double.

❓ Predict Output

advanced

Effect of converting logical array to double

What is the output of this MATLAB code?

l = [true false true];
d = double(l);
disp(d);

MATLAB

l = [true false true];
d = double(l);
disp(d);

A [2 1 2]

B [true false true]

C [0 0 0]

D [1 0 1]

💡 Hint

Logical true converts to 1, false to 0 when cast to double.

Converting logical true to double gives 1, false gives 0. So the output is [1 0 1].

❓ Predict Output

expert

Output of converting cell array of mixed types to numeric array

What error or output does this MATLAB code produce?

c = {1, '2', 3};
a = cell2mat(c);

MATLAB

c = {1, '2', 3};
a = cell2mat(c);

A [1 2 3]

B [1 '2' 3]

C Error: cell2mat cannot convert cell array with mixed types

D [1 0 3]

💡 Hint

cell2mat requires all cells to be numeric arrays of compatible sizes.

cell2mat fails if the cell array contains mixed types like numeric and char. It throws an error.