Safe Handling of Pointers
Pointers are variables that store the memory address of another variable. They are powerful in C because they allow you to directly access and manipulate memory. However, pointers are also risky: improper use can lead to bugs such as crashes, memory corruption, or unpredictable program behavior. One common source of errors is dereferencing a pointer that does not point to a valid memory location.
main.c
12345678910#include <stdio.h> int main() { int *unsafe_ptr = NULL; // This pointer is NULL // Unsafe: Dereferencing a NULL pointer (will likely crash) printf("%d\n", *unsafe_ptr); // Causes undefined behavior return 0; }
This first example shows what happens when you dereference a NULL pointer — it leads to undefined behavior and often crashes the program. Look at a safer version that includes proper checks before using pointers.
main.c
123456789101112131415161718192021#include <stdio.h> int main() { int value = 42; int *safe_ptr = &value; // Valid pointer int *unsafe_ptr = NULL; // NULL pointer // Safe: Check for NULL before dereferencing safe_ptr if (safe_ptr != NULL) printf("Safe pointer value: %d\n", *safe_ptr); else printf("safe_ptr is NULL\n"); // Safe: Check for NULL before dereferencing unsafe_ptr if (unsafe_ptr != NULL) printf("Unsafe pointer value: %d\n", *unsafe_ptr); else printf("unsafe_ptr is NULL\n"); return 0; }
Always check whether a pointer is NULL before dereferencing it. This simple defensive check prevents crashes and helps you identify logic errors early, keeping your programs more stable and predictable.
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Can you show me the safer version with proper pointer checks?
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Pyyhkäise näyttääksesi valikon
Pointers are variables that store the memory address of another variable. They are powerful in C because they allow you to directly access and manipulate memory. However, pointers are also risky: improper use can lead to bugs such as crashes, memory corruption, or unpredictable program behavior. One common source of errors is dereferencing a pointer that does not point to a valid memory location.
main.c
12345678910#include <stdio.h> int main() { int *unsafe_ptr = NULL; // This pointer is NULL // Unsafe: Dereferencing a NULL pointer (will likely crash) printf("%d\n", *unsafe_ptr); // Causes undefined behavior return 0; }
This first example shows what happens when you dereference a NULL pointer — it leads to undefined behavior and often crashes the program. Look at a safer version that includes proper checks before using pointers.
main.c
123456789101112131415161718192021#include <stdio.h> int main() { int value = 42; int *safe_ptr = &value; // Valid pointer int *unsafe_ptr = NULL; // NULL pointer // Safe: Check for NULL before dereferencing safe_ptr if (safe_ptr != NULL) printf("Safe pointer value: %d\n", *safe_ptr); else printf("safe_ptr is NULL\n"); // Safe: Check for NULL before dereferencing unsafe_ptr if (unsafe_ptr != NULL) printf("Unsafe pointer value: %d\n", *unsafe_ptr); else printf("unsafe_ptr is NULL\n"); return 0; }
Always check whether a pointer is NULL before dereferencing it. This simple defensive check prevents crashes and helps you identify logic errors early, keeping your programs more stable and predictable.
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