问题
vector<string> ExprTree::tokenise(string expression){
vector<string> store;
string s;
std::stringstream in(expression);
while(in >> s) {
store.push_back(s);
}
return store;
}
When i input the arithmetic expression (5 + 5) + 5
i get the output:
(5
+
5)
+
5
However i want:
(
5
+
5
)
+
5
Also, the code only separates the strings between whitespaces, is it possible to tokenise a string that is written without whitespaces? i.e (5+5)+5
回答1:
2 Updates you can do to solve your problem:
string s;
while(in >> s)
//instead, do
char ch;
while(in >> ch)
and then to handle the case of a blank space (and a newline?) put an if condition
if(ch != ' ')
store.push_back(ch);
That is if your desired input are just single digits. You'll have to make a much complex parser to handle bigger numbers. To make more complex parsers, this function is helpful. http://www.cplusplus.com/reference/istream/istream/peek/
回答2:
You can use strtok, strtok_r or Boost tokenizer to do what you need.
These halp you to split your string by multiple delimiters.
if you want to split string with multiple threads, use strtok_r against strtok.
if you need an example, simply google it.
来源：https://stackoverflow.com/questions/43567224/c-tokenise-string-and-store-in-vector