Blog

String handling functions strlen, strcpy, strcmp, etc. in c++

Unlike the std::string built-in function library in the C++ programming language, the C language or C-style character data type string does not have member functions such as append(), length(), or find(). Instead, a user-defined program must use the C language standard library functions for string operations such as copying character string arrays, appending character strings, and comparing character strings.

String length method in C++.

To find the length of a C-style character string, i.e., character array numbers excluding the null terminator array point location, in an existing C++ program, C++ users can apply the strlen() function from the <cstring> library.

String length example in C++.

#include <iostream>

#include <cstring> // here we use the C header file/processor directive for the strlen() function.

using namespace std;

int main() {

char company[] = “Vcanhelpsu, Edtech Platform”;

cout << “Exact length of company string variable – ” << strlen(company) << endl; // Result – 27

return 0;

}

Explanation of string length program.

• In this example, the strlen() function indicates the character number of all array element information stored before the null terminator. Finally, it does not count the null character (‘\0’).

String copying method in C++.

To copy C-style character string array data type information from the source to the destination location in a C++ program, C++ users can apply the strcpy() function from the <cstring> library.

String copying example in C++.

#include <iostream>

#include <cstring> // Here we use the c header file/processor directive for the strcpy() function

using namespace std;

int main() {

char language1[] = “Vcanhelpsu, Edtech Platform”;

char language2[50]; // Here we create the destination array size sufficient

// Here it copies language1 string data info into language2 string data

strcpy(language2, language1);

cout << “Original string is – ” << language1 << endl;

cout << “Here copied string info is – ” << language2 << endl;

return 0;

}

Explanation of String copying program.

• In this example, the strcpy() function copies the contents of language1 into a character string in language2. A null terminator is indicated at the end. Here you fix the way the copied string and the null terminator are stored and represented in the destination language2 array.

String concatenation method in C++.

To concatenate two character array strings into C-style character string array data information in a C++ program, C++ users can apply the strcat() function from <cstring> to an existing C++ program.

String concatenation example in C++.

#include <iostream>

#include <cstring> // Here we use the C header file/processor directive for the strcat() function

using namespace std;

int main() {

char text1[100] = “Java programming, “;

char text2[] = “Python programming”;

// Here it concatenates text2 into text1 from the source location to the destination location

strcat(text1, text2);

cout << “Final concatenated join string is – ” << text1 << endl;

return 0;

}

Explanation of String concatenation program.

• In this example, the strcat() function appends the contents of text2 to text1. The destination string (text1) is a fixed-size array containing proper spaces to move or append the concatenated string.

String comparison method in C++.

Array data information in a C-style character string. To compare two different C-style string data information in a C++ program, C++ users can apply the strcmp() function from the <cstring> header file library.

String comparison example in C++.

#include <iostream>

#include <cstring> // here we use the C header file/processor directive for the strcmp() function.

using namespace std;

int main() {

char text1[] = “Vcanhelpsu”;

char text2[] = “Edtech”;

if (strcmp(text1, text2) == 0) {

cout << “Here Both strings are the same” << endl;

} else {

cout << “Here Both strings are different” << endl;

}

return 0;

}

Explanation of String comparison program.

• In this example, the strcmp() function compares two different text strings in lexicographically ordered order and returns an output statement.
• If both text1 and text2 are equal, it returns 0.
• If text1 is lexicographically less than text2, it returns a negative value.
• If text1 is lexicographically greater than text2, it returns a positive value.

Finding a character in a string method in C++.

To find a particular character in a C-style character string array data information string in a C++ program, C++ users can apply the strchr() function to <cstring>.

Finding a character example in C++.

#include <iostream>

#include <cstring> // Here we use the C header file/processor directive for the strchr() function

using namespace std;

int main() {

char text[] = “Vcanhelpsu, Edtech”;

// Here it finds the first occurrence of the u character in the given text array string ‘u’

char* ptr = strchr(text, ‘u’);

if (ptr != nullptr) {

cout << “Here the ‘u’ character was found at index location – ” << (ptr – text) << endl;

} else {

cout << “here ‘u’ character not found in text string ” << endl;

}

return 0;

}

Explanation of Finding a Character Program.

• In this example, the strchr() function finds the first character in a C-style string. It returns the search value as the first character in the current character array. If the find text character is not found, it returns the nullptr value as output.

Detail explanation of C-style String function

null terminator (‘\0’) method in C++.

In C++ programs, the null terminator (‘\0’) is a special character string termination point. The null pointer is used to indicate or mark the last text string element of a C-style string. The null pointer location is a required element in the string because C-style text strings do not store their text string length. Therefore, it provides a null terminator signal to indicate where the current string ends. Without a null pointer in a string literal, any string literal functions used on C-style strings (such as strlen(), strcpy(), etc.) will not know where the string ends. This can lead to undefined program behavior or memory errors in a program.