length

最大阵列尺寸的长度

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Syntax

L = length(X)

Description

L = length(X)returns the length of the largest array dimension inX. For vectors, the length is simply the number of elements. For arrays with more dimensions, the length is最大（大小（x））. The length of an empty array is zero.

Examples

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Number of Vector Elements

Open Live Script

Find the length of a uniformly spaced vector in the interval[5,10].

v = 5:10

v =1×65 6 7 8 9 10

L = length(v)

L = 6

Length of Rectangular Matrix

Open Live Script

Find the length of a 3-by-7 matrix of zeros.

X = zeros(3,7); L = length(X)

L = 7

String Array

Open Live Script

创建一个字符串数组并计算其长度，即每行元素的数量。

X = ["a""b"“C”;“ D”“ e”"f"]

X =2x3 string"a" "b" "c" "d" "e" "f"

L = length(X)

L = 3

Length of Structure Fields

Open Live Script

Create a structure with fields forDay和Month. Use thestructfunfunction to applylengthto each field.

S = struct('Day'，[1 13 14 26]，'Month',{{'扬','Feb','Mar'}})

S =struct with fields:Day: [1 13 14 26] Month: {'Jan' 'Feb' 'Mar'}

l = structFun（@（字段）长度（字段），s）

L =2×14 3

Input Arguments

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`X`—Input array
scalar|vector|matrix|multidimensional array

Input array, specified as a scalar, vector, matrix, or multidimensional array.

Complex Number Support:Yes

Tips

To find the number of characters in a string or character vector, use thestrlengthfunction.
lengthdoes not operate on tables. To examine the dimensions of a table, use theheight,width, orsizefunctions.

Extended Capabilities

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

This function fully supports tall arrays. For more information, seeTall Arrays.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
使用GPU CODER™为NVIDIA®GPU生成CUDA®代码。

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

This function fully supports thread-based environments. For more information, seeRun MATLAB Functions in Thread-Based Environment.

GPU Arrays
使用并行计算工具箱™在图形处理单元（GPU）上运行加速代码。

This function fully supports GPU arrays. For more information, seeRun MATLAB Functions on a GPU(Parallel Computing Toolbox).

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

This function fully supports distributed arrays. For more information, see运行具有分布式数组的MATLAB功能(Parallel Computing Toolbox).

length

Syntax

Description

Examples

Number of Vector Elements

Length of Rectangular Matrix

String Array

Length of Structure Fields

Input Arguments

`X`—Input array
scalar|vector|matrix|multidimensional array

Tips

Extended Capabilities

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
使用GPU CODER™为NVIDIA®GPU生成CUDA®代码。

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

GPU Arrays
使用并行计算工具箱™在图形处理单元（GPU）上运行加速代码。

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

See Also

MATLAB Documentation

金宝app

Introducing Deep Learning with MATLAB

length

Syntax

Description

Examples

Number of Vector Elements

Length of Rectangular Matrix

String Array

Length of Structure Fields

Input Arguments

X—Input arrayscalar|vector|matrix|multidimensional array

Tips

Extended Capabilities

Tall ArraysCalculate with arrays that have more rows than fit in memory.

C/C++ Code GenerationGenerate C and C++ code using MATLAB® Coder™.

GPU Code Generation使用GPU CODER™为NVIDIA®GPU生成CUDA®代码。

HDL Code GenerationGenerate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based EnvironmentRun code in the background using MATLAB®backgroundPoolor accelerate code with Parallel Computing Toolbox™ThreadPool.

GPU Arrays使用并行计算工具箱™在图形处理单元（GPU）上运行加速代码。

Distributed ArraysPartition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.

See Also

MATLAB Documentation

金宝app

Introducing Deep Learning with MATLAB

`X`—Input array
scalar|vector|matrix|multidimensional array

Tall Arrays
Calculate with arrays that have more rows than fit in memory.

C/C++ Code Generation
Generate C and C++ code using MATLAB® Coder™.

GPU Code Generation
使用GPU CODER™为NVIDIA®GPU生成CUDA®代码。

HDL Code Generation
Generate Verilog and VHDL code for FPGA and ASIC designs using HDL Coder™.

Thread-Based Environment
Run code in the background using MATLAB®`backgroundPool`or accelerate code with Parallel Computing Toolbox™`ThreadPool`.

GPU Arrays
使用并行计算工具箱™在图形处理单元（GPU）上运行加速代码。

Distributed Arrays
Partition large arrays across the combined memory of your cluster using Parallel Computing Toolbox™.