multiplication using addition

Question

i want to write a C program that calculates multiplication using addition, can someone help me?

Answer 1

//edited code of J Dombino , without 3rd variable "mult"
int num1;
int num2
;
for(int=1;i<=numb2;i++){
num1+=num1;
}

Answer 2

if(num 2!=0)
while(num2-->1) num1+=num1;
else num1=0;
//in case num2 is 0
//note : num2 can be -ve also , make code by yourself first for every possibility ... if any problem comes ... then ask , I am following the thread
//hint : use if else

Answer 3

You can use a for loop wich iterate num2 times adding num1 each time:

int num1;
int num2
int mult=0; //result
for(int=1;i<=numb2;i++){
mult += num1;
}

Answer 4

thank u all :)

Answer 5

yeah, you save 32 bits, but you lose the original value of num1 which could be used after the for loop.

Answer 6

i know but my teacher asked us to multiply two numbers without using the multiplication so i have to use the loop

Answer 7

for(i=1;i<=num2;i++){
prod=num1*i;
}

The code will multiply two numbers correctly but it will do stupid iterations for example if num1 = 2 and num2 = 3:

The first iteration will set prod=2*1=2
The second iteration prod=2*2=4
The third prod=2*3=6

so in the first two iteration the machine is wasting its time. You can directly multiply the two numbers prod=num1*num2 without any for loop;

Answer 8

Then use my first code, your teacher is going to give you a 10/10

Answer 9

is this correct? https://code.sololearn.com/caa72w8IM022/?ref=app