56:68：错误：预期表达

Question

I am trying to understand the last argument of find_if which is giving compilation errors. Any pointers on documentation in the context of this problem on the usage of [](int ch) will be really helpful. http://en.cppreference.com/w/cpp/algorithm/find

Seeing compilation error with one of the argument.

https://leetcode.com/playground/U5SLW8zq

median.cpp:56:68: error: expected expression input.erase(input.begin(), find_if(input.begin(), input.end(), [](int ch) { ^ median.cpp:62:55: error: expected expression input.erase(find_if(input.rbegin(), input.rend(), [](int ch) {

void trimLeftTrailingSpaces(string &input) {
    input.erase(input.begin(), find_if(input.begin(), input.end(), [](int ch) {
        return !isspace(ch);
    }));
}

void trimRightTrailingSpaces(string &input) {
    input.erase(find_if(input.rbegin(), input.rend(), [](int ch) {
        return !isspace(ch);
    }).base(), input.end());
}

Answer 1

The issue was due to the missing compiler option. I could compile using c++11

$ g++ -std=c++11 median.cpp