How to check if a string contains a char?

问题

I have a text file that I want to read. I want to know if one of the lines contains [ so I tried :

if(array[i] == "[")

But this isn't working.

How can I check if a string contains a certain character?

回答1:

Look at the documentation string::find

std::string s = "hell[o";
if (s.find('[') != std::string::npos)
    ; // found
else
    ; // not found

回答2:

If the array is char* array or char array[], you can find a char through a while loop:

while(i < nSize)
    if (array[i] == '[')

Note: '[' is the correct char literal, but "[" is a string literal.

回答3:

To check if a character of a string is equal to a particular character, you need to check in the below manner:

if(array.at(i) == '[') {
}

Check below link for more details: https://www.geeksforgeeks.org/string-at-in-cpp/##targetText=string%20at()%20in%20C%2B%2B,characters%20from%20a%20given%20string.&targetText=Syntax%202%3A,first%20character%20has%20index%200)

来源：https://stackoverflow.com/questions/43629363/how-to-check-if-a-string-contains-a-char