[英]Extract integer from a string
我有一个类似“ yx-name”的字符串,其中y和x是从0到100的数字。从此字符串中,将c提取为整数变量的最佳方法是什么?
You could split the string by .
您可以将字符串分割为
.
and convert it to integer type directly. 并将其直接转换为整数类型。 The second number in while loop is the one you want, see sample code:
while循环中的第二个数字是您想要的数字,请参见示例代码:
template<typename T>
T stringToDecimal(const string& s)
{
T t = T();
std::stringstream ss(s);
ss >> t;
return t;
}
int func()
{
string s("100.3-name");
std::vector<int> v;
std::stringstream ss(s);
string line;
while(std::getline(ss, line, '.'))
{
v.push_back(stringToDecimal<int>(line));
}
std::cout << v.back() << std::endl;
}
It will output: 3 它将输出:3
It seem that this thread has a problem similar to you, it might help ;) 似乎该线程有一个与您类似的问题,可能有帮助;)
Use two calls to unsigned long strtoul( const char *str, char **str_end, int base )
, eg: 使用两个调用来对
unsigned long strtoul( const char *str, char **str_end, int base )
,例如:
#include <cstdlib>
#include <iostream>
using namespace std;
int main(){
char const * s = "1.99-name";
char *endp;
unsigned long l1 = strtoul(s,&endp,10);
if (endp == s || *endp != '.') {
cerr << "Bad parse" << endl;
return EXIT_FAILURE;
}
s = endp + 1;
unsigned long l2 = strtoul(s,&endp,10);
if (endp == s || *endp != '-') {
cerr << "Bad parse" << endl;
return EXIT_FAILURE;
}
cout << "num 1 = " << l1 << "; num 2 = " << l2 << endl;
return EXIT_FAILURE;
}
You can achieve it with boost::lexical_cast , which utilizes streams like in billz' answer: Pseudo code would look like this (indices might be wrong in that example): 您可以使用boost :: lexical_cast来实现它,它利用像Billz的答案中那样的流:伪代码看起来像这样(该示例中的索引可能是错误的):
std::string yxString = "56.74-name";
size_t xStart = yxString.find(".") + 1;
size_t xLength = yxString.find("-") - xStart;
int x = boost::lexical_cast<int>( yxString + xStart, xLength );
Parsing errors can be handled via exceptions that are thrown by lexical_cast. 可以通过lexical_cast引发的异常来处理解析错误。 For more flexible / powerful text matching I suggest boost::regex .
为了更灵活/更强大的文本匹配,我建议使用boost :: regex 。
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