strcat — Concatenate text inputs element-wise with MATLAB-compatible implicit expansion and trailing-space handling.

strcat concatenates text inputs element-wise across compatible array sizes. It supports MATLAB-compatible string, char, and cellstr container forms with implicit expansion semantics.

Syntax

out = strcat(str1, str2, ...)

Inputs

Returns

Errors

How strcat works

• Inputs are concatenated element-wise. Scalars expand across arrays of matching dimensions using MATLAB's implicit expansion rules.
• When at least one input is a string array (or string scalar), the result is a string array. <missing> values propagate, so any missing operand yields a missing result for that element.
• When no string arrays are present but any input is a cell array of character vectors, the result is a cell array whose elements are character vectors.
• Otherwise, the result is a character array. For character inputs, strcat removes trailing space characters from each operand before concatenating.
• Cell array elements must be character vectors (or string scalars). Mixing cell arrays with unsupported content raises a MATLAB-compatible error.
• Empty inputs broadcast naturally: an operand with a zero-length dimension yields an empty output after broadcasting.

Does RunMat run strcat on the GPU?

RunMat currently performs text concatenation on the CPU. When any operand resides on the GPU, the runtime gathers it to host memory before applying MATLAB-compatible trimming and concatenation rules. Providers do not need to implement device kernels for this builtin today.

GPU memory and residency

No. String manipulation runs on the CPU. If intermediate values are on the GPU, RunMat gathers them automatically so you can call strcat without extra residency management.

Examples

Concatenate string scalars element-wise

greeting = strcat("Run", "Mat")

Expected output:

greeting = "RunMat"

Concatenate a string scalar with a string array

names = ["VM", "Turbine", "Accelerate"];
tagged = strcat("runmat-", names)

Expected output:

tagged = 1×3 string
    "runmat-VM"    "runmat-Turbine"    "runmat-Accelerate"

Concatenate character arrays while trimming trailing spaces

A = char("GPU ", "Planner");
B = char("Accel", " Stage ");
result = strcat(A, B)

Expected output:

result =

  2×11 char array

    'GPUAccel'
    'PlannerStage'

Concatenate cell arrays of character vectors

C = {'Run ', 'Plan '; 'Fuse ', 'Cache '};
suffix = {'Mat', 'Ops'; 'Kernels', 'Stats'};
combined = strcat(C, suffix)

Expected output:

combined = 2×2 cell
    {'RunMat'}    {'PlanOps'}
    {'FuseKernels'}    {'CacheStats'}

Propagate missing strings during concatenation

values = [string(missing) "ready"];
out = strcat("job-", values)

Expected output:

out = 1×2 string
    <missing>    "job-ready"

Broadcast a scalar character vector across a character array

labels = char("core", "runtime", "planner");
prefixed = strcat("runmat-", labels)

Expected output:

prefixed =

  3×11 char array

    'runmat-core'
    'runmat-runtime'
    'runmat-planner'

Using strcat with coding agents

Open a RunMat example with live inputs, then ask the agent to explain how strcat changes the result.

FAQ

Related Strings functions

Open-source implementation

Unlike proprietary runtimes, every RunMat function is open-source. Read exactly how strcat is executed, line by line, in Rust.

• View the source for strcat in Rust on GitHub
• Learn how the RunMat runtime works
• Found a bug? Open an issue with a minimal reproduction.

About RunMat

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