从字符串中提取子字符串

# 固定位置提取
text = "Hello, World!"
substring = text[7:12]
print(substring)  # 输出: World

# 基于条件的提取
import re
pattern = r'\d+'
match = re.search(pattern, text)
if match:
    print(match.group())  # 输出: (如果有数字)

# 动态位置提取
start = 7
length = 5
substring = text[start:start+length]
print(substring)  # 输出: World

// 固定位置提取
let text = "Hello, World!";
let substring = text.substring(7, 12);
console.log(substring);  // 输出: World

// 基于条件的提取
let match = text.match(/\d+/);
if (match) {
    console.log(match[0]);  // 输出: (如果有数字)
}

// 动态位置提取
let start = 7;
let length = 5;
let substring = text.substring(start, start + length);
console.log(substring);  // 输出: World

text = "Hello, World!"
start = 7
length = 5
if start + length <= len(text):
    substring = text[start:start+length]
else:
    substring = "索引越界"
print(substring)

import re
text = "Hello, World!"
pattern = r'\d+'
match = re.search(pattern, text)
if match:
    print(match.group())
else:
    print("未找到匹配项")