First character of string c ++ [closed]

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First character of string c ++ [closed]

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Good, I would like to know when the first character of a string is "#" and I do not know what function to use. Can somebody help me?

string c++

asked by nerviosus 18.12.2017 в 23:29

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score 6 · Accepted Answer

A string of characters is nothing more than an array of characters (the class std::string encapsulates this same complexity). So, and taking into account that the indexes in C ++ start at 0, you have a wide range of possibilities to choose from:

std::string cadena = "ABCDEF";
std::cout << cadena[0]            // (1)
          << cadena.at(0)         // (2)
          << cadena.front()       // (3) 
          << *cadena.begin()      // (4)
          << *std::begin(cadena); // (5)

Index operator

at is similar to the index operator. Check that the index is valid and if it does not throw an exception

Direct access to the first character of the string

Using iterators

Another way to use iterators

So to know if the first character is '#' it is enough to apply the comparison operator to one of the options we have just seen:

if( cadena.front() == '#' )
{
  // ...
}