Functions in C/C++ - examples
If you want to learn about the functions in C and C++, visit the webpage: Functions in C/C++
1. Replacement of the position
Load two integers of X and Y. Create a function that changes the positions of two integer variables. Use this function and replace the values with X and Y variables.
2. Is the number simple?
Make a function that determines whether a number is simple. Enter a natural number and examine whether it's free.
3. Printing the array
Enter n. Then Enter n elements of that array. Create a special method for writing it. Use that method to print the array elements on the screen.
4. Extracting even elements of an array
Enter an array of n elements. The number n, as well as the elements of the array, is entered by the user. Create a method that overwrites even elements from the initial array. Use the created method to extract even elements from the initial sequence.
5. Number of repetitions of a certain character
Enter some text from the keyboard. Create a special function that counts the passed character. Use the function to determine the number of repetitions of the letter "p" in the entered text.
6. Daily earnings
Michael is employed part-time and earns a daily income for his work. He writes down the dates and the value of that day's earnings in his notebook because he keeps records of it. Create a program that will help Michael to load date values with earnings that are entered so that one date with daily earnings can be loaded in one row. Create a function that separates the dates and earnings from the passed array of daily earnings into two separate arrays in which these data are defined, the date as a string and the earnings as a real number. The date is entered in the format dd_mm__yyyy (date, month, year)
Example:
Input:
12_2_2021 2045.33
23_8_2021 1034.66
15_4_2021 1567.99
Output:
Array 1:
12.02.2021
23.08.2021
15.04.2021
Array 2:
2045.31
1034.66
1567.99
Example:
Input:
12_2_2021 2045.33
23_8_2021 1034.66
15_4_2021 1567.99
Output:
Array 1:
12.02.2021
23.08.2021
15.04.2021
Array 2:
2045.31
1034.66
1567.99
7. Login
Create a method (function) for user login based on entering a username and password. Allow the user to attempt a maximum of 3 password attempts. The method should give an answer whether the user is successfully logged in or not. Call the function from the main method. If the method returns that the user is logged in, then print the message: "The user is successfully logged in", otherwise write "The user is not successfully logged in". The username and password combination is known to be correct: admin user.
Example:
Input:
Enter your username and password:
"Tot"
"user1"
Re-enter incorrect password
"admin"
"user"
Exit:
The user is successfully logged in
Example:
Input:
Enter your username and password:
"Tot"
"user1"
Re-enter incorrect password
"admin"
"user"
Exit:
The user is successfully logged in
8. Daily earnings
Mihajlo is employed part-time and earns a daily income for his work. He writes down the dates and the value of that day's earnings in his notebook because he keeps records of it. Create a program that will help Mihajlo to load date values with earnings that are entered so that one date with daily earnings can be loaded in one row. Create a function that separates the dates and earnings from the passed string of daily earnings into two separate strings in which these data are defined, the date as a string and the earnings as a real number. The date is entered in the format dd_mm__yyyy (date, month, year).
Example:
Input:
12_2_2021 2045.33
23_8_2021 1034.66
15_4_2021 1567.99
Output:
Array1:
12.02.2021
23.08.2021
15.04.2021
Array2:
2045.31
1034.66
1567.99
Example:
Input:
12_2_2021 2045.33
23_8_2021 1034.66
15_4_2021 1567.99
Output:
Array1:
12.02.2021
23.08.2021
15.04.2021
Array2:
2045.31
1034.66
1567.99
9. Login
Create a method (function) for user login based on entering a username and password. Allow the user to attempt a maximum of 3 password attempts. The method should give an answer whether the user is successfully logged in or not. Call the function from the main method. If the method returns that the user is logged in, then print the message: "The user is successfully logged in", otherwise write "The user is not successfully logged in". The username and password combination is known to be correct: admin user.
Example:
Input:
Enter your username and password:
"Mika"
"user1"
Re-enter incorrect password
"admin"
"user"
Output:
The user is successfully logged in
Example:
Input:
Enter your username and password:
"Mika"
"user1"
Re-enter incorrect password
"admin"
"user"
Output:
The user is successfully logged in
10. Determination of the maximum
Create a function that determines the maximum of two integers passed as function parameters.
Enter two integers and determine their maximum using the previously defined function.
Enter two integers and determine their maximum using the previously defined function.
Create the function "maximum()", which receives two integers, a and b, as parameters, and then, inside the function, examine which of them is larger.
If "a" is greater, the function should return "a" as a return value, otherwise "b".
Inside the main function, enter two integers, then call the previously created maximum function to determine it. Print that value in the rest of the program.
#include < stdio.h>
/*Solution for C programming language*/
int maximum(int a, int b)
{
int main()
{
/*Solution for C programming language*/
int maximum(int a, int b)
{
if(a>b)
{
else
{
}{
return a;
}else
{
return b;
}int main()
{
int a,b,maxAB;
printf("a=?,b=?\n");
scanf("%d%d",&a,&b);
maxAB = maximum(a,b);
printf("Maximum is %d",maxAB);
return 0;
}printf("a=?,b=?\n");
scanf("%d%d",&a,&b);
maxAB = maximum(a,b);
printf("Maximum is %d",maxAB);
return 0;
11. Determining whether a number is prime
Create a function that checks if the number passed to it as a parameter is prime. Enter an integer and determine if it is prime using the previously defined function.
Read more about prime numbers on the website: A prime numbers and factoring
Read more about prime numbers on the website: A prime numbers and factoring
#include < stdio.h>
/*Solution in the programming language C*/
int prime(int a)
{
int main()
{
/*Solution in the programming language C*/
int prime(int a)
{
int res=1;
if(a==1 || a==2){
int d=2;
while(d < a){
}if(a==1 || a==2){
return 1;
}int d=2;
while(d < a){
if(a % d == 0){
d++;
}
return res;
res=0;
break;
}break;
d++;
int main()
{
int x;
printf("x=?\n");
scanf("%d",&x);
if(prime(x)){
else{
return 0;
}printf("x=?\n");
scanf("%d",&x);
if(prime(x)){
printf("The number %d is prime",x);
}else{
printf("The number %d isn't prime",x);
}return 0;
12. Writing bits from left to right
Write a function that prints the bits of x from left to right.
Create a function "bits()", which receives an integer "a" as a parameter.
Inside the function, use a loop to create powers of 2, starting with 215, and then decrease the exponent through the cycles.
Check in each cycle, whether that power of two is less than the rest of the number, which is initially equal to the whole number "a" sent.
If yes, print 1 as bit, if not, print zero. Recalculate the remainder of the number that remains when we subtract the current power of 2 from the previous remainder.
In the main "main" function, call the previously created function to be executed.
#include < stdio.h>
/*Solution in the programming language C*/
int bits(int a)
{
int main()
{
/*Solution in the programming language C*/
int bits(int a)
{
int rem = x; //7
for(int i = 15;i >= 0;i--){
printf("\n");
}for(int i = 15;i >= 0;i--){
int a=(int)pow(2,i);
if(a <= rem){
else{
}if(a <= rem){
printf("1 ");
rem=rem % a; //a=4, rem =7%4=3; a=2, rem =3%2=1; a=1, rem =1%1=0
}rem=rem % a; //a=4, rem =7%4=3; a=2, rem =3%2=1; a=1, rem =1%1=0
else{
printf("0 ");
}printf("\n");
int main()
{
int x;
printf("x=?\n");
scanf("%d",&x);
bits(x);
return 0;
}printf("x=?\n");
scanf("%d",&x);
bits(x);
return 0;
13. Rounding to K decimal places.
Write a function that prints the quotient of natural numbers M/N to k decimal places
Enter three integers M,N and K. (eg 13,3,2)
Find the quotient M/N, (eg 13/3=4.333333), and choose double or float as the data type, in order to save the decimals.
Multiply the resulting number by 10K, and then convert that number into a whole number, so that it contains both the digits of the result and the digits that should be displayed after the decimal point (eg 433).
Extract the integer result from this number, by dividing by 10K, as well as the decimal part by looking for the remainder of the division by 10K.
Print the integer part first, then put "." and add the decimal part below.
#include < stdio.h>
/*Solution in programming language C*/
int main()
{
/*Solution in programming language C*/
int main()
{
int M,N,K,res,coef;
double resD;
printf("M=?,N=?,K=?\n");
scanf("%d%d%d",&M,&N,&K); //13,3,2
resD=(double)M/N; //4.333333
printf("res=%f\n",resD);
coef=(int)pow(10,K); //100
res=resD*coef; //433
resD=(double)res/coef; //4.3300000
printf("res=%g\n",resD);
int num,dec;
num=res/coef; //4
dec=res % coef; //33
printf("%d.%d\n",num,dec);
}double resD;
printf("M=?,N=?,K=?\n");
scanf("%d%d%d",&M,&N,&K); //13,3,2
resD=(double)M/N; //4.333333
printf("res=%f\n",resD);
coef=(int)pow(10,K); //100
res=resD*coef; //433
resD=(double)res/coef; //4.3300000
printf("res=%g\n",resD);
int num,dec;
num=res/coef; //4
dec=res % coef; //33
printf("%d.%d\n",num,dec);
14. Combinatorics-Calculation of combinations.
Write a program to calculate
for the given natural numbers n,k,p S=Cn k-Cn k+1 +..+(-1) p*Cn k+p,
according to the formula for calculating combinations
for the given natural numbers n,k,p S=Cn k-Cn k+1 +..+(-1) p*Cn k+p,
according to the formula for calculating combinations
15. Bit in the given position.
Write a function that reports whether there is a 1 at position pos, the argument of the function (parameter) X. The bit positions are numbered, from right to left, starting from position 1.
16. Number in reverse order.
If the number M1 is obtained from the number M by writing its digits in inverse order, write a program that prints all pairs of three-digit numbers (a,b) that have the property: If A*B=C, then A1*B1=C1. E.g:
312 * 221 = 68952
213 * 122 = 25986
312 * 221 = 68952
213 * 122 = 25986
17. The closest number that satisfies the condition.
If S(n) denotes the sum of digits in the decimal notation of the number n, determine n such that it is the nearest number smaller than 2003, for which the equality holds:
n+S(n)+S(S(n))+S(S(S(n)))+S(S(....S(n)....)=2003
n+S(n)+S(S(n))+S(S(S(n)))+S(S(....S(n)....)=2003
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