C Programming Strings Overview

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Questions and Answers

What is the return value of strcmp() when two strings are identical?

-1

0 (correct)

Which header file is required to use the strcat() function?

<stdlib.h>

<stdio.h>

<ctype.h>

<string.h> (correct)

What does the strcat() function do in C programming?

Finds the length of a string

Compares two strings

Concatenates two strings (correct)

Copies one string to another

What is the correct way to declare a string in C?

char str[] = "Hello"; Signup and view all the answers

What happens if the destination array in strcat() is not large enough?

It causes a buffer overflow Signup and view all the answers

How can you manually copy a string without using strcpy()?

Use loops to iterate over each character Signup and view all the answers

What will the output of strcmp(str1, str2) be if str1 = "abcd" and str2 = "abCd"?

1 Signup and view all the answers

What data type is returned by the strcat() function?

char * Signup and view all the answers

What happens when the input contains a space in the scanf() function?

Only the part before the space is stored. Signup and view all the answers

Why don't we use '&' with the char array in scanf()?

The array name automatically points to the address of the first element. Signup and view all the answers

What is the return type of the strlen() function?

size_t Signup and view all the answers

What is the purpose of the strcpy() function?

To copy one string to another. Signup and view all the answers

What will be the output of strlen() for the string 'Hello'?

5 Signup and view all the answers

Which header file is required for using standard string functions like strcpy() and strlen()?

<string.h> Signup and view all the answers

What does the strcat() function do?

It concatenates two strings. Signup and view all the answers

What is the correct syntax for the strcpy() function?

char strcpy(char* destination, const char* source); Signup and view all the answers

What is the correct way to declare a string in C programming?

char s[5]; Signup and view all the answers

Which statement is true about string initialization in C?

char c[] = 'hi'; Signup and view all the answers

What will happen if you try to assign a string to a declared char variable in C?

It will throw a compile-time error. Signup and view all the answers

What function can be used to read a string input from the user?

scanf() Signup and view all the answers

Which of the following string initializations is incorrect?

char c = "abc"; Signup and view all the answers

How does the compiler treat a string enclosed in double quotation marks?

It appends a null character at the end. Signup and view all the answers

In which scenario will you likely encounter an error regarding string declaration?

Trying char c = "Too many characters"; Signup and view all the answers

Which of the following operations is NOT valid for strings in C?

Using the assignment operator after declaration. Signup and view all the answers

Study Notes

Strings

Strings in C are sequences of characters terminated by a null character (\0).
When enclosed in double quotes, the compiler automatically adds the null character.
Example: char c[] = "cstring";
Declaring a string of 5 characters: char s[5];
Initializing strings: Various methods exist.
- char c[] = "abcd";
- char c[50] = "abcd";
- char c[] = {'a', 'b', 'c', 'd', '\0'};
- char c[5] = {'a', 'b', 'c', 'd', '\0'};
Important: Avoid assigning strings longer than the declared array size (e.g., char c[5] = "abcde";). This is incorrect and will lead to issues.
Arrays and strings are not assignable in C after declaration (e.g., char c[100]; c = "C programming"; is incorrect).
Reading strings: Use scanf("%s", name); to read a string from the user, but this stops at whitespace.

Standard Library String Functions

strlen(): Calculates the length of a given string.
- Returns a size_t value (an unsigned integer).
- Defined in <string.h>.
strcpy(): Copies a string to another.
- Takes two arguments: destination string, source string, both of type char.
- Copies the source until the null terminator.
- Returns the copied string (destination string).
- Defined in <string.h>
strcmp(): Compares two strings character by character.
- Returns 0 if they are equal.
- Returns a non-zero value if they're not equal. Positive if the first string is lexicographically larger.
- Defined in <string.h>.
strcat(): Concatenates (joins) two strings.
- Takes the destination and the source strings as arguments (destination needs space for the combined string).
- Adds the source string to the end of the destination string.
- Returns a pointer to the destination string (which is now modified).
- Defined in <string.h>.

String Operations without Library Functions

Copying a string: Use loops to copy characters one by one, ensuring the destination string has enough space. Handles truncation if the destination is shorter.
Finding string length: Use a loop to count characters until the null terminator is found.

Structures

Structures are used to group variables of different data types together.
Example: struct employee {int id; char name[100]; float salary;};
Declaring a structure variable: struct employee emp1;
Accessing structure members: Use the dot operator: emp1.id = 101; strcpy(emp1.name,"John Doe");
Declaring a structure with variables: struct employee emp1, emp2;
Data types used:
int, char, float, double, etc.
Array of Structures:
- Stores multiple structures.
- Used to store data about collections of different entities.
- Example: struct student st[5]; for storing information about 5 students.

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Description

This quiz covers the fundamentals of strings in C programming, including their declaration, initialization, and the use of standard library string functions. Test your understanding of string characteristics and the importance of null termination in C.