Written: August 14, 2026
Finding a maximum is the pattern behind many later algorithms: keep a champion, challenge it with each next value.
This walkthrough keeps the logic small and readable so you can type it, run it, and then change one input at a time to see what happens.
What you will build
Initialize the max with the first element, then walk the rest of the array updating whenever you see a larger value.
- Read n and the array
- Set max = a[0]
- Loop from index 1 to n-1 updating max
- Print max
Working C example
#include <stdio.h>
int main(void) {
int n, i, max;
int a[100];
printf("Enter count (1-100): ");
if (scanf("%d", &n) != 1 || n < 1 || n > 100) return 1;
for (i = 0; i < n; i++) {
if (scanf("%d", &a[i]) != 1) return 1;
}
max = a[0];
for (i = 1; i < n; i++) {
if (a[i] > max) max = a[i];
}
printf("Maximum = %d\n", max);
return 0;
}How the logic works
Read the program top to bottom: includes and main first, then the statements that change variables, then the print that proves the result.
If your output looks wrong, print the variables before and after the critical lines. That single habit catches most beginner bugs faster than rewriting the whole file.
Starting max at 0 fails for all-negative arrays. Starting from a[0] avoids that trap.
Common mistakes
Forgetting a semicolon, using the wrong format specifier in printf/scanf, and mixing up assignment (=) with comparison (==) are the usual culprits.
Compile with warnings enabled (`gcc -Wall`) so the compiler points at risky casts and unused variables before you chase them by hand.
Try this next
Change the sample inputs, add a second test case, and briefly note what stayed the same. Teaching yourself with tiny experiments sticks better than copying a longer program you never run.
When you can explain every line without looking, you are ready for the next exercise in the series.
