Overview

If you combine different integer types in a matrix (e.g., signed with unsigned, or 8-bit integers with 16-bit integers), MATLAB^®returns a matrix in which all elements are of one common type. MATLAB sets all elements of the resulting matrix to the data type of the leftmost element in the input matrix. For example, the result of the following concatenation is a vector of three 16-bit signed integers:

A = [int16(450) uint8(250) int32(1000000)]

A = 1×3 int16 row vector 450 250 32767

Example of Combining Unlike Integer Sizes

Concatenate the following two numbers once, and then switch their order. The return value depends on the order in which the integers are concatenated. The leftmost type determines the data type for all elements in the vector:

A = [int16(5000) int8(50)]

A = 1×2 int16 row vector 5000 50

B = [int8(50) int16(5000)]

B = 1×2 int8 row vector 50 127

The first operation returns a vector of 16-bit integers. The second returns a vector of 8-bit integers. The elementint16(5000)is set to127, the maximum value for an 8-bit signed integer.

The same rules apply to vertical concatenation:

C = [int8(50); int16(5000)]

C = 2×1 int8 column vector 50 127

Example of Combining Signed with Unsigned

Now do the same exercise with signed and unsigned integers. Again, the leftmost element determines the data type for all elements in the resulting matrix:

一个= [int8 (-100) uint8(100)]

A = 1×2 int8 row vector -100 100

B = [uint8(100) int8(-100)]

B = 1×2 uint8 row vector 100 0

The elementint8(-100)is set to zero because it is no longer signed.

MATLAB evaluates each elementprior toconcatenating them into a combined array. In other words, the following statement evaluates to an 8-bit signed integer (equal to 50) and an 8-bit unsigned integer (unsigned -50 is set to zero) before the two elements are combined. Following the concatenation, the second element retains its zero value but takes on the unsignedint8type:

一个= [int8 (50), uint8(-50)]

A = 1×2 int8 row vector 50 0