21 32 F:\文档\上机文件\上级文件\fourth\student.cpp [Error] cannot convert 'const float*' to 'const char*' for argument '1' to 'size_t strlen(const char*)'出现的原因
时间: 2023-06-27 10:07:06 浏览: 61
这个错误是因为你在调用 `strlen` 函数时传递了一个 `const float*` 类型的参数,但是 `strlen` 函数只接受 `const char*` 类型的参数。这是因为 `strlen` 函数用于计算字符串的长度,而字符串是以 `char` 类型的数组形式存储的。
你需要检查一下代码,看一下是哪个变量或参数被错误地声明为了 `float` 类型,然后将其改为 `char` 类型或 `const char*` 类型即可。
相关问题
std::string str("test string"); const char* a = str.c_str(); const char* b = std::string(a).c_str(); std::string test_string(b);这段代码为啥会崩溃,请用英文回答。
This code may crash because the variable "b" points to the memory location of "a", which is a temporary pointer returned by the "c_str()" function of the "str" object. When the temporary "std::string" object is destroyed after the second line, the memory location pointed to by "b" becomes invalid. Thus, when the "test_string" object is created in the fourth line using this invalid pointer, it may cause undefined behavior, including a segmentation fault or memory corruption.
Csharp 正则表达式获取02.01.23 08:30:21,并分别获取六个数字
您可以使用正则表达式的分组语法来获取每个数字。以下是一个使用正则表达式获取 "02.01.23 08:30:21" 字符串及其六个数字的示例代码:
```csharp
string input = "some text 02.01.23 08:30:21 some more text";
string pattern = @"(\d{2})\.(\d{2})\.(\d{2})\s(\d{2}):(\d{2}):(\d{2})";
Match match = Regex.Match(input, pattern);
if (match.Success)
{
Console.WriteLine("Match found: " + match.Value);
Console.WriteLine("First number: " + match.Groups[1].Value);
Console.WriteLine("Second number: " + match.Groups[2].Value);
Console.WriteLine("Third number: " + match.Groups[3].Value);
Console.WriteLine("Fourth number: " + match.Groups[4].Value);
Console.WriteLine("Fifth number: " + match.Groups[5].Value);
Console.WriteLine("Sixth number: " + match.Groups[6].Value);
}
else
{
Console.WriteLine("Match not found");
}
```
输出结果为:
```
Match found: 02.01.23 08:30:21
First number: 02
Second number: 01
Third number: 23
Fourth number: 08
Fifth number: 30
Sixth number: 21
```
在上面的代码中,使用了正则表达式的分组语法来将六个数字分别匹配到不同的捕获组中。使用 `match.Groups` 属性可以获取这些捕获组。其中,捕获组的编号从 1 开始,而不是从 0 开始。因此,第一个捕获组可以通过 `match.Groups[1].Value` 获取。