Question 1

Q1: What is a string in C?

Accepted Answer

A string in C is a sequence of characters terminated by a null character (\0). It is essentially an array of characters, where the last element is always the null terminator that signals the end of the string.

Question 2

Q2: How do you declare a string in C?

Accepted Answer

A string can be declared in two ways:
As a character array:
char str[10] = "Hello";
Using a pointer to a string literal:
char *str = "Hello";

Question 3

Q3: What is the difference between character arrays and string literals?

Accepted Answer

A character array stores the string in a modifiable memory location, while a string literal points to a fixed memory location (typically read-only), which means modifying a string literal may lead to undefined behavior.

Question 4

Q4: What is the purpose of the null character (\0) in a string?

Accepted Answer

The null character (\0) indicates the end of the string. It tells string functions like strlen() and printf() where the string stops.

Question 5

Q5: How do you input a string from the user?

Accepted Answer

You can use functions like scanf(), gets(), or the safer alternative fgets() to take string input:
scanf() stops reading at the first whitespace.
gets() reads the entire line but is unsafe due to possible buffer overflow.
fgets() is safe and allows you to specify the buffer size.
Example:
char str[100];
fgets(str, 100, stdin);

Question 6

Q6: What are the most commonly used string functions in C?

Accepted Answer

Some of the most commonly used string manipulation functions (from string.h) are:
strlen() – Returns the length of the string.
strcpy() – Copies one string to another.
strcat() – Concatenates two strings.
strcmp() – Compares two strings.
strncpy() – Copies a specified number of characters.
strchr() – Finds the first occurrence of a character in a string.
strstr() – Finds a substring within a string.

Question 7

Q7: What is the difference between strcpy() and strncpy()?

Accepted Answer

strcpy(destination, source) copies the entire source string into destination, including the null terminator.
strncpy(destination, source, n) copies only the first n characters from source to destination, and does not automatically append a null character unless n is smaller than the string length.

Question 8

Q8: How do you concatenate two strings in C?

Accepted Answer

You can concatenate two strings using the strcat() function. The source string is appended to the destination string.
char dest[100] = "Hello ";
char src[] = "World";
strcat(dest, src); // dest becomes "Hello World"

Question 9

Q9: How do you compare two strings in C?

Accepted Answer

The strcmp() function is used to compare two strings. It returns:
0 if the strings are equal.
A positive value if the first string is greater than the second.
A negative value if the first string is less than the second.
int result = strcmp(str1, str2);

Question 10

Q10: What is the difference between scanf() and gets() for reading strings?

Accepted Answer

scanf() reads a string until it encounters a whitespace (space, tab, newline), which means it cannot read multiple words.
gets() reads the entire line, including spaces, but it is unsafe and can cause buffer overflows.

Question 11

Q11: Why is fgets() preferred over gets()?

Accepted Answer

fgets() is safer because it prevents buffer overflow by allowing the programmer to specify the maximum number of characters to read. Unlike gets(), it also stops reading at the newline or end of the buffer.

Question 12

Q12: Can you modify string literals in C?

Accepted Answer

No, string literals in C are stored in a read-only memory location. Attempting to modify a string literal can lead to undefined behavior.

Question 13

Q13: How do you find the length of a string?

Accepted Answer

You can use the strlen() function to find the length of a string. It returns the number of characters in the string, excluding the null terminator.
int length = strlen(str);

Strings in C Programming Language

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