8.4. A Comparison of the `string` Class and C-Strings

The following table lists some operations programs often need to perform. The table details how C++ supports these operations for C-strings and string objects. The following references provide a complete list and greater detail.

string class and member functions
string class relational operators (select the C++14 for the most up to date list)
string/number conversion functions
C-string functions

`string` Class	C-String

Creation & Initialization
`string s1("hello");` `string s2("world");`	`char* s1 = "hello";` (content of s1 is constant) `char s2[50] = "world";` (content of s2 can change)
Creation Empty
`string s3;`	`char s3[100] = "";` `char s3[100];` + `s3[0] = '\0';`
Input / Read
`string s4;` `getline(cin, s4);`	`char s4[50];` `cin.getline(s4, 50);`
Test For Equality
`s1 == s2`	`strcmp(s1,s2) == 0` `!strcmp(s1,s2)`
Test For Inequality
`s1 != s2`	`strcmp(s1,s2) != 0` `strcmp(s1,s2)`
Ordering
`s1 < s2` (does s1 come before s2)	`strcmp(s1,s2) < 0`
`s1 <= s2`	`strcmp(s1,s2) <= 0`
`s1 > s2` (does s1 come after s2)	`strcmp(s1,s2) > 0`
`s1 >= s2`	`strcmp(s1,s2) >= 0`
`s1.compare(s2)`	`strcmp(s1,s2)`
Character Access
`s1[i]` no bounds checking `s1.at(i)` bounds checking enabled	`s1[i]` no bounds checking
`st.front()`	`s1[0]`
`s1.back()`	`s1[strlen(s1) - 1]`
Length Operations
`s1.length()` `s1.size()`	`strlen(s1)`
`s1.empty()`	`strlen(s1) == 0`
Clearing (Complete Data Removal)
`s1.clear()` `s1.erase()`	`s1[0] = '\0'`
Shortening (Partial Data Removal)
`s1.erase(start)`	`s1[start] = '\0'`
Copying
`s3 = s1`	`strcpy(s3, s1)`
Concatenation
`s3 += s2`	`strcat(s3, s2)`
`s3 = s1 + s2`
Searching
`s1.find("llo")` ¹ (find substring, left to right)	`strstr(s1, "llo")`
`s1.rfind("llo")` ¹ (find substring, reverse or right to left)
`s1.find('h')` ² (find character, left to right)	`strchr(s1, 'h')`
`s1.rfind('h')` ² (find character, reverse or right to left)	`strrchr(s1, 'h')`
`s1.find_first_of("llo")` ^{1, 3} (find character, left to right)	`strpbrk(s1, "llo")`
`s1.find_last_of("llo")` ^{1, 3} (find character, reverse or right to left)
`s1.find_first_of('h')` ²	`strchr(s1, 'h')`
`s1.find_last_of('h')` ²	`strrchr(s1, 'h')`
string ↔ C-string
Convert string to C-string `s1.c_str();` `s1.data();`	Convert C-string to string `string s4("Hello");` `string s5(s1);`

The argument may be either a string or a C-string.
For single character arguments, find and find_first_of perform the same search, and rfind and find_last_of perform the same search.
Locates any single character in the argument string.