Predict the Output of C Program Examples: 12 Tricky Questions With Answers

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Predict the Output of C Program Examples: 12 Tricky Questions With Answers

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Are you diving into C programming and struggling with those head-scratching moments? Predicting the output of c program examples can feel like a puzzle, especially when tricky behaviors like operator precedence, pointer arithmetic, or undefined actions trip you up. This guide breaks down 12 challenging C programs with step-by-step explanations and exact outputs. Perfect for beginners sharpening skills or pros brushing up for interviews.

Whether you're hunting for Output of c program examples with solutions or exploring Output of c program examples w3schools style tutorials, these examples build real intuition. Let's jump in—no fluff, just code and clarity.

Question 1: Precedence Puzzle


c
#include <stdio.h>
int main() {
int x = 5 + 3 * 2;
printf("%d", x);
return 0;
}

Output: 11

Multiplication binds tighter than addition, so 3*2=6, then 5+6=11. Classic operator precedence—always check it!

Question 2: Post-Increment Trick


c
#include <stdio.h>
int main() {
int a = 10;
printf("%d %d", a++, a);
return 0;
}

Output: 10 11

Post-increment prints the original value first (10), then updates a to 11. Sequencing matters here.

Question 3: Pointer Arithmetic Surprise


c
#include <stdio.h>
int main() {
int arr[] = {1, 2, 3};
int *p = arr;
printf("%d", *(p + 1));
return 0;
}

Output: 2

p+1 skips to the next int (4 bytes), dereferencing gives arr=2. Pointers treat arrays as contiguous memory.​

Question 4: Logical AND Short-Circuit


c
#include <stdio.h>
int main() {
int x = 0;
printf("%d", (x && printf("Hi")) ? 1 : 0);
return 0;
}

Output: 0

&& short-circuits: x is false, so printf("Hi") never runs. Efficient, but sneaky for side effects.

Question 5: Comma Operator Secret


c
#include <stdio.h>
int main() {
int x = (5, 3 + 2);
printf("%d", x);
return 0;
}

Output: 5

Comma evaluates left-to-right, but the value is the last one (3+2=5). Ignores the 5 on the left.

Question 6: Array Initialization Gotcha


c
#include <stdio.h>
int main() {
int arr[2] = {1, 2, 3};
printf("%d %d %d", arr[0], arr[1], arr[2]);
return 0;
}

Output: 1 2 0 (or garbage for arr in some compilers)​

Extra initializers are ignored; unset elements are zeroed in some cases, but rely on explicit sizing to avoid undefined behavior.

Question 7: Bitwise Shift Shenanigans


c
#include <stdio.h>
int main() {
int x = 1 << 31;
printf("%d", x);
return 0;
}

Output: -2147483648 (on 32-bit signed int)

Left shift on signed int overflows into sign bit, causing negative value due to two's complement.

Question 8: Ternary with Side Effects


c
#include <stdio.h>
int main() {
int x = 5;
int y = (x > 3) ? x++ : x--;
printf("%d %d", x, y);
return 0;
}

Output: 6 5

Ternary picks x++ (true branch): y gets original x=5, then x increments to 6. Unspecified order in some compilers—avoid!

Question 9: String Literal Mystery


c
#include <stdio.h>
int main() {
char *s = "Hello";
s[0] = 'h';
printf("%s", s);
return 0;
}

Output: Undefined (crash or garbage)

String literals are read-only in modern C. Modifying triggers undefined behavior—use char arrays instead.

Question 10: Loop Variable Scope


c
#include <stdio.h>
int main() {
int i;
for (i = 0; i < 3; i++) {
printf("%d", i);
}
printf("%d", i);
return 0;
}

Output: 0123

Loop var i persists post-loop with final value 3. No block scope in old C standards.

Question 11: Floating-Point Equality


c
#include <stdio.h>
int main() {
float a = 0.1f;
float b = 0.1f;
printf("%d", a == b);
return 0;
}

Output: 1

Same literal initializes identically, so equal. But 0.1 + 0.2 != 0.3 due to precision—use epsilon checks.

Question 12: Recursive Mayhem


c
#include <stdio.h>
int main() {
static int x = 5;
if (x > 0) {
printf("%d ", x);
x--;
main();
}
return 0;
}

Output: 5 4 3 2 1

Static retains value across recursive calls. Counts down to 1, then stops. Stack overflow risk for deeper recursion!

Mastering these sharpens your debugging eye. Practice with C Programs for practice or grab Output of c program examples pdf, C programming examples pdf, 100 C programs PDF, or even 1000 C Programming examples PDF for more drills.

Compile these in your IDE and tweak them—hands-on beats theory every time. What's your toughest C puzzle so far?


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