String C & C++

 C-strings (#include <cstring>) C++ strings (#include <string>)

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Declaring a C-string variable           Declaring a C++ string object
-----------------------------           -----------------------------
char str[10];                           string str;

Initializing a C-string variable        Initializing a C++ string object
--------------------------------        --------------------------------
char str1[11] = "Call home!";           string str1("Call home!");
char str2[] = "Send money!";            string str2 = "Send money!";
char str3[] = {'O', 'K', '\0'};         string str3("OK");
Last line above has same effect as:
char str3[] = "OK";
                                        string str4(10, 'x');
                                        
Assigning to a C-string variable        Assigning to a C++ string object
--------------------------------        --------------------------------
Can't do it, i.e., can't do this:       string str;
char str[10];                           str = "Hello";
str = "Hello!";                         str = otherString;

Concatenating two C-strings             Concatenating two C++ string objects
---------------------------             ------------------------------------
strcat(str1, str2);                     str1 += str2;
strcpy(str, strcat(str1, str2));        str = str1 + str2;

Copying a C-string variable             Copying a C++ string object
---------------------------             ---------------------------
char str[20];                           string str;
strcpy(str, "Hello!");                  str = "Hello";
strcpy(str, otherString);               str = otherString;

Accessing a single character            Accessing a single character
----------------------------            ----------------------------
str[index]                              str[index]
                                        str.at(index)
                                        str(index, count)
                                        
Comparing two C-strings                 Comparing two C++ string objects
-----------------------                 --------------------------------
if (strcmp(str1, str2) < 0)             if (str1 < str2)
    cout << "str1 comes 1st.";              cout << "str1 comes 1st.";
if (strcmp(str1, str2) == 0)            if (str1 == str2)
    cout << "Equal strings.";               cout << "Equal strings.";
if (strcmp(str1, str2) > 0)             if (str1 > str2)
    cout << "str2 comes 1st.";              cout << "str2 comes 1st.";
    
Finding the length of a C-string        Finding the length of a C++ string object
--------------------------------        -----------------------------------------
strlen(str)                             str.length()

Output of a C-string variable           Output of a C++ string object
-----------------------------           -----------------------------
cout << str;                            cout << str;
cout << setw(width) << str;             cout << setw(width) << str;