Day_4

Charecter array:

int main(){
    char char_array1[] = {'a','b','c','d','\0'};
    cout<< char_array1;   //abcd

    char char_array2[] = {'x','y','z'};
    cout<<char_array2;    //xyzabcd

    char char_array3[] = "xyz"; 
    cout<<char_array3;    //xyz
}

Wile creating an charecter array always put a \0 charecter at the end other wise it will store garbage. Thats why in the end case we got xyzabcd instade of xyz.

cin.getline() method:

You cant just use cin to take a whole sentance as input as cin dont excepts spaces, so if it get any space in the input it terminates the input right there. Here comes cin.getline() comes to help. it take some arguments,

• 1st the name of the char array
• 2nd the max length of the char array
• (optional) the Delimiter (e.g. '\0','$' etc.)

String:

• string contains char array internally.

int main(){
    string s1 = "hello world";
    char arr[] = {'h','e','l','l','o','\0'};

    string s2(arr);
    cout<< s2;              // hello
}

• check a array is empty or not.

int main(){
    string s1 = "hello world";
    if(s1.empty()){          // returns bool value
        cout<<"its empty";
    }

}

• append a string with a string,

int main(){
    string s1 = "hello world";
    s1.append(" its soumyadip");
    cout<<s1;                // hello world its soumyadip
}

• clear all charecter from a string,

int main(){
    string s1 = "hello world";
    cout<<s1.length();                 // 11
    s1.clear();
    cout<<s1.length();                // 0
}

• compare two strings,

int main(){
    string s1 = "hello world";
    cout<<s1.compare(s1);  //0
    string s2 = "wejofnjsafnlds";
    cout<<s1.compare(s2);  // some value may be -ve or +ve
}

you can also use less than and greater than operators to compare. This comparison happens lexographically.

• find and remove a substring

int main(){
    string s1 = "hello world";
    int idx = s1.find("world");
    cout<<idx<<endl;            // 7
    // erase
    string word = "world";
    int len = word.length();
    s1.erase(idx,len+1);
    cout<<s1<<endl;            // "hello "
    
}