Hash table in C: solved exercise with chaining

This exercise is scheduled for daily publication and follows the same didactic structure used across the site: clear statement, compilable code, and expected output.

Problem statement

Implement a practical example of the topic and validate the output in the console.

C solution

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#include <stdio.h>
#include <stdlib.h>

#define TAM 7

typedef struct Nodo {
    int clave;
    struct Nodo *sig;
} Nodo;

int hash(int clave) { return clave % TAM; }

void insertar(Nodo *tabla[], int clave) {
    int i = hash(clave);
    Nodo *n = (Nodo *)malloc(sizeof(Nodo));
    n->clave = clave;
    n->sig = tabla[i];
    tabla[i] = n;
}

int main(void) {
    Nodo *tabla[TAM] = {0};
    insertar(tabla, 10);
    insertar(tabla, 17);
    insertar(tabla, 24);
    printf("Bucket de 10: %d\n", hash(10));
    return 0;
}

Expected output

1
Bucket de 10: 3

Common mistakes

Not validating input and standard-library return values.
Ignoring edge cases (buffers, limits, null pointers).
Skipping basic compile/run verification.

Practical use

Hash tables are the structure behind dictionaries, caches, sets, and almost every O(1) amortized lookup.

Recommended next exercise

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FAQ

Is this exercise useful for C exams and technical interviews?

Yes. It targets patterns that commonly appear in practice assignments, technical interviews, and C programming exams.

Where can I keep practicing with more solved C exercises?

In Programming in C in 100 Solved Exercises and C Exercises. Kindle Unlimited: View on Amazon.

How should I practice this exercise type to improve faster?

Start with small inputs, run edge cases (empty, one item, max capacity), then rewrite the solution from scratch without copying.