# 检查字符串长度

在脚本中经常需要检查字符串长度，bash提供了多种方法:

```bash
${#strvar}
expr length $strvar
expr “${strvar}”:’.*’
echo $strvar | wc -c
echo $strvar |awk '{print length}'
```

## 使用 "#" 符号计算字符串长度(推荐)

最常用的shell字符串长度计算是使用符号 `#` :

```bash
string="Learn Bash Programming with LinuxHint"
echo ${#string}
```

## 使用 `expr` 来计算字符串长度

`expr` 命令可以计算字符串长度

```bash
string="Hypertext Markup Language"
len=`expr length "$string"`
echo "The length of string is $len"
```

> 通用性差些，在macos的zsh上语法不兼容

## 使用 `wc` 统计字符串长度(不推荐)

`wc` 命令的 `-c` 参数可以计算字符串长度:

```bash
string="Hypertext Markup Language"
echo $string | wc -c
```

> 使用 `wc -c` 统计不准确 很奇怪

## 使用 `awk` 加笋字符串长度

```bash
string="Hypertext Markup Language"
echo $strvar |awk '{print length}'
```

## 参考

* [Find Length of String in Bash](https://linuxhint.com/length_of_string_bash/)


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://huataihuang.gitbook.io/cloud-atlas-draft/develop/shell/bash/check_string_length.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.