How Strings Work Differently Across Languages in DSA C - Debugging & Practice

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this C string code?

Consider this C code snippet that manipulates strings using pointers. What will be printed?

DSA C

char str[] = "hello";
char *p = str;
p++;
printf("%c\n", *p);

A o

B h

C l

D e

💡 Hint

Remember that p++ moves the pointer to the next character in the array.

The pointer p initially points to 'h'. After p++, it points to 'e'. So, *p is 'e'.

❓ Predict Output

intermediate

What happens when you modify a string literal in C?

What will happen when running this C code?

DSA C

char *str = "hello";
str[0] = 'H';
printf("%s\n", str);

A Prints 'Hello'

B Runtime error (segmentation fault)

C Prints 'hello'

D Compilation error

💡 Hint

String literals are stored in read-only memory in many systems.

Modifying a string literal causes undefined behavior, often a segmentation fault at runtime.

🔧 Debug

advanced

Why does this string copy code cause a problem?

Examine this code that copies a string. What is the issue?

DSA C

char *src = "hello";
char dest[5];
strcpy(dest, src);
printf("%s\n", dest);

A src is a pointer, cannot be used with strcpy

B strcpy requires dynamic memory allocation for dest

C dest array is too small, missing space for null terminator

D No problem, prints 'hello'

💡 Hint

Remember that strings in C end with a null character '\0'.

dest has size 5, but 'hello' plus '\0' needs 6 bytes, causing buffer overflow.

🧠 Conceptual

advanced

How are strings stored differently in C compared to higher-level languages?

Which statement best describes how strings work in C compared to languages like Python or Java?

A C strings are arrays of characters ending with a null byte; higher-level languages use objects with length metadata

B C strings are immutable like in Java; Python strings are mutable arrays

C C strings are objects with methods; Python and Java use raw character arrays

D C strings store length explicitly; Python and Java use null-terminated strings

💡 Hint

Think about how C strings know where they end.

C strings are simple arrays ending with '\0'. Python and Java strings are objects that store length and other info.

🚀 Application

expert

What is the output after this pointer manipulation on a C string?

Given the code below, what will be printed?

DSA C

char str[] = "world";
char *p = str + 2;
*(p + 1) = 'x';
printf("%s\n", str);

A worxd

B worxd\0

C woxld

D world

💡 Hint

Look carefully at which character is changed by *(p + 1) = 'x'.

p points to 'r' (index 2). p+1 points to 'l' (index 3). Changing it to 'x' makes string 'worxd'.