C Programming
C programming
Check some challenge problems in C here.
Example programs.
This program prints odds numbers from 1 to N:
#include <stdio.h>
*********************************************************************************************
Read multiple user inputs.
Write two scanf statements to get input values into birthMonth and birthYear. Then write a statement to output the month, a slash, and the year. End with newline.
#include <stdio.h>
*********************************************************************************************
Output simple text with newlines.
Write code that prints the following. End each output line with a newline.
A1 B2
Note: Whitespace (blank spaces / blank lines) matters; make sure your whitespace exactly matches the expected output.
#include <stdio.h>
int main(void) {
printf("A1\n");
printf("B2\n");
return 0;
}
*********************************************************************************************
Output text and variable.
Write a statement that outputs variable numCars as follows. End with a newline.
There are 99 cars.
#include <stdio.h>
int main(void) {
int numCars = 99;
printf("There are %d cars.\n", numCars);
return 0;
}
*********************************************************************************************
Read user input and print to output.
Write a statement that reads an integer into userNum, and a second statement that prints userNum followed by a newline.
#include <stdio.h>
int main(void) {
int userNum = 0;
scanf("%d", &userNum);
printf("%d\n", userNum );
return 0;
}
*********************************************************************************************
Read multiple user inputs.
Write two statements to get input values into birthMonth and birthYear. Then write a statement to output the month, a slash, and the year. End with newline.
#include <stdio.h>
int main(void) {
int birthMonth;
int birthYear;
scanf("%d", &birthMonth);
scanf("%d", &birthYear);
printf("%d/%d\n", birthMonth, birthYear);
return 0;
}
*********************************************************************************************
Basic syntax errors.
Corrected:
#include <stdio.h>
int main(void) {
int userNum;
userNum = 5;
printf("Predictions are hard.\n");
printf("Especially ");
printf("about the future.\n");
printf("Num is: %d\n", userNum);
return 0;
}
*********************************************************************************************
More syntax errors.
Retype the statements, correcting the syntax errors.
printf("Num: %d\n", songnum);
printf("%d\n", int songNum);
printf("%d songs\n" songNum);
#include <stdio.h>
int main(void) {
int songNum;
songNum = 5;
printf("Num: %d\n", songNum);
printf("%d\n", songNum);
printf("%d songs\n", songNum);
return 0;
}
*********************************************************************************************
Array calculator in C.
Multiplying arrays in C
Example program using switch statements
/* Copyright ©TheBookdale
This program is the start of project 2 - A Matrix Calculator*/
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
int main(void){
int i, j, k; //used in for loops
double matrixA[10][10]; // initialized at 10 just to have it initialized
double matrixB[10][10];
int rowA, colA;
int rowB, colB;
double sumM[10][10]; //sum operation matrix
double subM[10][10]; //substration operation matrix
double scaM[10][10]; //scalar operation matrix
double mulM[10][10]; //multiplication operation matrix
char operation = ' ';//used in swtich statements
char again = 'Y';
double scalar = 0.0;
while (again == 'Y'){
//this is the operation menu just type A, B, C or D to calculate
printf("\nOperation Menu\n");
printf("\t A to Add\n");
printf("\t B to Subtract\n");
printf("\t C to Scalar Multiply\n");
printf("\t D to Multiply two matrices\n");
printf("Enter yout choice: ");
scanf(" %c", &operation);
operation = toupper(operation);//this will convert the letter input into a capital letter, this way the switch statement will work well
switch (operation){
case 'A':
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
while ((rowA != rowB) && (colA != colB)){
printf("\nMatrices must be the same size\n");
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
}
printf("\n\tEnter elements of Matrix A a %d x %d matrix.\n", rowA, colA); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
scanf("%lf", &matrixA[i][j]); // we tell the program where to store the values
}
}
printf("\n\tEnter elements of Matrix B a %d x %d matrix.\n", rowB, colB); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowB; i++){
for (j = 0; j < colB; j++){
scanf("%lf", &matrixB[i][j]); // we tell the program where to store the values
}
}
printf("\nThe Sum of matrixA + matrixB is : \n");
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
sumM[i][j] = matrixA[i][j] + matrixB[i][j];
printf("%.1lf\t", sumM[i][j]);
}
printf("\n");
}
break;
case 'B':
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
while ((rowA != rowB) && (colA != colB)){
printf("\nMatrices must be the same size\n");
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
}
printf("\n\tEnter elements of Matrix A a %d x %d matrix.", rowA, colA); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
scanf("%lf", &matrixA[i][j]); // we tell the program where to store the values
}
}
printf("\n\tEnter elements of Matrix B a %d x %d matrix.", rowB, colB); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowB; i++){
for (j = 0; j < colB; j++){
scanf("%lf", &matrixB[i][j]); // we tell the program where to store the values
}
}
printf("\nThe difference between matrixA - matrixB is : \n");
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
subM[i][j] = matrixA[i][j] - matrixB[i][j];
printf("%.1lf\t", subM[i][j]);
}
printf("\n");
}
break;
case 'C':
printf("Enter the scalar: ");
scanf("%lf", &scalar);
printf("\nThe scalar is: %.1lf ", scalar);
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("\n\tEnter elements of Matrix A a %d x %d matrix.", rowA, colA); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
scanf("%lf", &matrixA[i][j]); // we tell the program where to store the values
}
}
printf("\nThe scalar multiplication between matrixA * %.1lf is: \n", scalar);
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
scaM[i][j] = scalar * matrixA[i][j];
printf("%.1lf\t", scaM[i][j]);
}
printf("\n");
}
break;
case 'D':
//when mulotiplying arrays matrixA colum # has to equal matrixB row #
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
// Column of first matrix should be equal to column of second matrix and
while (colA != rowB)
{
printf("\n\nError! column of first matrix not equal to row of second.\n\n");
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
}
// Storing elements of first matrix.
printf("\n\tEnter elements of Matrix A a %d x %d matrix.", rowA, colA); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowA; i++){
for (j = 0; j < colA; j++){
scanf("%lf", &matrixA[i][j]); // we tell the program where to store the values
}
}
// Storing elements of second matrix.
printf("\n\tEnter elements of Matrix B a %d x %d matrix.", rowB, colB); // with the %d we remember the user the dimentions of the array
for (i = 0; i < rowB; i++){
for (j = 0; j < colB; j++){
scanf("%lf", &matrixB[i][j]); // we tell the program where to store the values
}
}
// Initializing all elements of result matrix to 0
for (i = 0; i<rowA; ++i)
for (j = 0; j<colB; ++j)
{
mulM[i][j] = 0;
}
// Multiplying matrices a and b and
// storing result in result matrix
for (i = 0; i<rowA; ++i)
for (j = 0; j<colB; ++j)
for (k = 0; k<colA; ++k)
{
mulM[i][j] += matrixA[i][k] * matrixB[k][j];
}
// Displaying the result
printf("\nOutput Matrix:\n");
for (i = 0; i<rowA; ++i)
for (j = 0; j<colB; ++j)
{
printf("%.1lf ", mulM[i][j]);
if (j == colB - 1)
printf("\n\n");
}
break;
default:
printf("\nIncorrect option! Please choose option A-D.");
break;
}
printf("\n\nDo you want to calculate again? Y/N\n");
scanf(" %c", &again);
again = toupper(again);
}
printf("\n\nGoodbye!\n\n");
return 0;
}
*********************************************************************************************
Calculating area a geometrical figures with user defined functions
/*This program calculates area of various geometrical shapes*/
#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <stdio.h>
#include <math.h>
#define M_PI 3.14159265358979323846
//User Defined Function Declaration
double triangleArea(int b, int h);
double circleArea(int r);
double rectangleArea(int b, int h);
int main(void){
int x, y, radius;
char operation = ' ';
char loop = 'Y';
while (loop == 'Y'){
printf("\tGeometrical Shapes Calculator\n\n");
printf("What would you like to calculate the are of?\n\n");
printf("\t1.\tTriangle\n");
printf("\t2.\tCircle\n");
printf("\t3.\tRectangle\n");
printf("\t4.\tSquare\n\n");
printf("Enter an option(1,2,3,4): ");
scanf(" %c", &operation);
operation = toupper(operation);
switch (operation){
case 'A':
printf("Enter base: ");
scanf("%d", &x);
printf("\nEnter height: ");
scanf("%d", &y);
printf("\nThe Triangle area is: %.2lf.\n", triangleArea(x, y));
break;
case 'B':
printf("Radius: ");
scanf("%d", &radius);
printf("\nThe circle area is: %.2lf\n", circleArea(radius));
break;
case 'C':
printf("Enter base: ");
scanf("%d", &x);
printf("\nEnter width: ");
scanf("%d", &y);
printf("\nThe rectangle area is: %.2lf\n", rectangleArea(x,y));
break;
case 'D':
printf("Enter square side lenght: ");
scanf("%d", &x);
printf("\nThe square area is: %.2lf\n", rectangleArea(x,x));
break;
default:
printf("\nIncorrect option! Please choose a number 1-4.");
break;
}
printf("\nDo you want to calculate again? Y/N\n");
scanf(" %c", &loop);
loop = toupper(loop);
}
printf("\n\nGoodbye!");
return 0;
}
//User Defined Function Definition
double triangleArea(int b, int h){
double area;
area = (b*h) / 2;
return area;
}
double circleArea(int r){
double area;
area = M_PI*(r*r);
return area;
}
double rectangleArea(int b, int h){
double area;
area = b * h;
return area;
}
*********************************************************************************************
matrix calculator with user defined functions
/*
Copyright ©TheBookdale. All rights reserved.
This program calculates the addition, subtraction and multiplication of matrices
as well as a scalar multiplication
(PROJECT 3)
*/
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
//User Defined Function Declaration
void readMatrix(int array[10][10], int rows, int colums);
void printMatrix(int array[10][10], int rows, int colums);
void matrixAddSub(int arrayone[10][10], int arraytwo[10][10], int rows, int colums, int mul);
void matrixScalarMultiply(int array[10][10], int scalar, int rows, int colums);
void matrixMultiply(int arrayone[10][10], int arraytwo[10][10], int rowsA, int columsA, int columsB);
int main(void){
int i, j, k; //used in for loops
int matrixA[10][10]; // initialized at 10 just to have it initialized
int matrixB[10][10];
int rowA, colA;
int rowB, colB;
int operation;//used in swtich statements
char again = 'Y';
int scalar = 0;
int add = 1;
int sub = -1;
while (again == 'Y'){
//this is the operation menu just type A, B, C or D to calculate
printf("\nOperation Menu\n");
printf("\t1. to Add\n");
printf("\t2. to Subtract\n");
printf("\t3. to Scalar Multiply\n");
printf("\t4. to Multiply two matrices\n");
printf("Enter yout choice: ");
scanf(" %d", &operation);
switch (operation){
case 1:
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
while ((rowA != rowB) && (colA != colB)){
printf("\nMatrices must be the same size\n");
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
}
printf("\n\tEnter elements of Matrix A a %d x %d matrix.\n", rowA, colA); // with the %d we remember the user the dimentions of the array
readMatrix(matrixA, rowA, colA);
printf("\n\t\tMatrix A\n\n");
printMatrix(matrixA, rowA, colA);
printf("\n\tEnter elements of Matrix B a %d x %d matrix.\n", rowB, colB); // with the %d we remember the user the dimentions of the array
readMatrix(matrixB, rowB, colB);
printf("\n\t\tMatrix B\n\n");
printMatrix(matrixB, rowB, colB);
printf("\nThe Sum of matrixA + matrixB is : \n");
matrixAddSub(matrixA, matrixB, rowA, colA, add);
break;
case 2:
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
while ((rowA != rowB) && (colA != colB)){
printf("\nMatrices must be the same size\n");
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("Enter the #rows and #cols for matrix B: ");
scanf("%d%d", &rowB, &colB);
}
printf("\n\tEnter elements of Matrix A a %d x %d matrix.\n", rowA, colA); // with the %d we remember the user the dimentions of the array
readMatrix(matrixA, rowA, colA);
printf("\n\t\tMatrix A\n\n");
printMatrix(matrixA, rowA, colA);
printf("\n\tEnter elements of Matrix B a %d x %d matrix.\n", rowB, colB); // with the %d we remember the user the dimentions of the array
readMatrix(matrixB, rowB, colB);
printf("\n\t\tMatrix B\n\n");
printMatrix(matrixB, rowB, colB);
printf("\nThe difference between matrixA - matrixB is : \n");
matrixAddSub(matrixA, matrixB, rowA, colA, sub);
break;
case 3:
printf("\nEnter the scalar: ");
scanf("%d", &scalar);
printf("\nThe scalar is: %d ", scalar);
printf("\nEnter the #rows and #cols for matrix A: ");
scanf("%d%d", &rowA, &colA);
printf("\n\tEnter elements of Matrix A a %d x %d matrix.\n", rowA, colA); // with the %d we remember the user the dimentions of the array
readMatrix(matrixA, rowA, colA);
printf("\n\t\tMatrix A\n\n");
printMatrix(matrixA, rowA, colA);
printf("\nThe scalar multiplication between matrixA * %d is: \n", scalar);
matrixScalarMultiply(
*********************************************************************************************
Pythagorean Triple function in C
/*
Copyright ©TheBookdale. All rights reserved.
This program checks to see if user inputs represent a Pythagorean Triple
*/
#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <math.h>
// User Defined Function Declaration
int pythagoreanTriple(int x, int y, int z);
int main(void){
int a, b, c;
char loop = 'Y';
while (loop == 'Y' || loop == 'y'){
printf("This program verifies if inputs represent a Pythagorean Triple\n\n");
printf("Enter values for a, b, and c: ");
scanf("%d%d%d", &a, &b, &c);
pythagoreanTriple(a, b, c);
printf("\n\nDo you want to calculate again? Y/N\n");
scanf(" %c", &loop);
}
printf("\nGoodbye!\n\n");
return 0;
}
int pythagoreanTriple(int x, int y, int z){
int triple;
if (pow(x, 2) + pow(y, 2) == pow(z, 2)){
triple = 1;
printf("triple = %d\n", triple);
printf("%d, %d and %d are Pythagorean Triple triple\n", x, y, z);
}
else{
triple = 0;
printf("triple = %d\n", triple);
printf("%d, %d and %d are not Pythagorean Triple triple\n", x, y, z);
}
return triple;
}
*********************************************************************************************
Complex numbers basic calculator
#include <stdio.h>
int main (void){
double a, b, c, d;
double realsum, imagsum, realsub, imagsub, realmul, imagmul, realdivt, imagdivt, realdivb, realdiv, imagdiv;
printf("\nEnter the first set of numbers: ");
scanf("%lf%lf", &a, &b);
printf("\nEnter the second set of numbers: ");
scanf("%lf%lf", &c, &d);
realmul = (a*c) + (b*d)*(-1);
imagmul = (a*d) + (b*c);
realsum = a+c;
imagsum = b+d;
realsub = a-c;
imagsub = b-d;
realdivt = a*c +b*d;
imagdivt = a*d*(-1) + b*c;
realdivb = c*c + d*d;
realdiv = realdivt/realdivb;
imagdiv = imagdivt/realdivb;
printf("The sum of (%.2lf %.2lfi) + (%.2lf %.2lfi) = %.2lf %.2lfi\n\n", a, b, c, d, realsum, imagsum);
printf("The substraction (%.2lf %.2lfi)-(%.2lf %.2lfi) = %.2lf %.2lfi\n\n", a, b, c, d, realsub, imagsub);
printf("The multiplication (%.2lf %.2lfi)*(%.2lf %.2lfi) = %.2lf %.2lfi\n\n", a, b, c, d, realmul, imagmul);
printf("The divition (%.2lf %.2lfi) / (%.2lf %.2lfi) = %.2lf %.2lfi\n\n", a, b, c, d, realdiv, imagdiv);
return 0;
}
*********************************************************************************************
Calculating change.
/*This program calculates change in different coins. This program combines user defined functions and pointers.
Enjoy the code
*/
#include <stdio.h>
void ComputeChange(int totCents, int* quartersChange, int* dimesChange, int* nickelsChange, int* penniesChange) { // FIXME add four pass by pointer parameters
int cents = 0;
*quartersChange = totCents / 25;
cents = totCents - (*quartersChange * 25);
*dimesChange = cents / 10;
cents = cents - (*dimesChange * 10);
*nickelsChange = cents / 5;
cents = cents - (*nickelsChange * 5);
*penniesChange = cents;
return;
}
int main(void) {
int totalCents = 67; // Total amount of change needed
int quartersChange = 0; // Number of quarters used for change
int dimesChange = 0; // Number of dimes used for change
int nickelsChange = 0; // Number of nickels used for change
int penniesChange = 0; // Number of pennies used for change
ComputeChange(totalCents, &quartersChange, &dimesChange, &nickelsChange, &penniesChange); // FIXME Add four pointer arguments
printf("Change for %d cents is:\n", totalCents);
printf("\t%d quarters\n", quartersChange);
printf("\t%d dimes\n", dimesChange);
printf("\t%d nickels\n", nickelsChange);
printf("\t%d pennies\n", penniesChange);
return 0;
}
Working with strings
Write a C program that finds the length of a string, and finds the total number of letter 't' in that string.
#include <stdio.h>
#include <string.h>
int
main (void)
{
char str1[70] =
"Why do mathematicians like parks? Because of all the natural logs.";
char str2[70] =
"Why did the programmer quit his job? Because he didn't get arrays.";
char str3[70] =
"What did the force day to the distance? We're having a moment.";
int len1 = 0;
int len2 = 0;
int len3 = 0;
int t1 = 0;
int t2 = 0;
int t3 = 0;
int i = 0;
len1 = strlen (str1);
len2 = strlen (str2);
len3 = strlen (str3);
printf ("String lenght 1 : %d \n", len1);
printf ("String lenght 2 : %d\n", len2);
printf ("String lenght 3 : %d\n", len3);
for (i = 0; i < len1; i++){
if (str1[i] == 't'){
t1 = t1 + 1;
}
}
for (i = 0; i < len2; i++){
if (str2[i] == 't'){
t2 = t2 + 1;
}
}
for (i = 0; i < len3; i++){
if (str3[i] == 't'){
t3 = t3 + 1;
}
}
printf ("String 1 has %d t's\n", t1);
printf ("String 2 has %d t's\n", t2);
printf ("String 3 has %d t's\n", t3);
return 0;
}