manual tracing in C

1. Structured Programming Language
Manual Tracing, Basic Loop, 1D Array
Mohammad Imam Hossain,
Lecturer, CSE, UIU

2. Tracing
#include<stdio.h>
int main()
{
int i=0, x=0;
for(i=1; i<10; ++i) {
if(i%2==1) {
x+=i;
}
else {
x--;
}
printf("%d, “ , x ) ;
}
printf("nx=%d“, x) ;
return 0;
}
i i%2==1 x (=0 initially) Output

3. Tracing
#include<stdio.h>
int main()
{
int i=0, x=0;
for(i=1; i<10; ++i) {
if(i%2==1) {
x+=i;
}
else {
x--;
}
printf("%d, “ , x ) ;
}
printf("nx=%d“, x) ;
return 0;
}
i i%2==1 x (=0 initially) Output
1 T x=x+i=0+1=1 1,

4. Tracing
#include<stdio.h>
int main()
{
int i=0, x=0;
for(i=1; i<10; ++i) {
if(i%2==1) {
x+=i;
}
else {
x--;
}
printf("%d, “ , x ) ;
}
printf("nx=%d“, x) ;
return 0;
}
i i%2==1 x (=0 initially) Output
1 T x=x+i=0+1=1 1,
2 F x--;
x=x-1=1-1=0
1, 0,

5. Tracing
#include<stdio.h>
int main()
{
int i=0, x=0;
for(i=1; i<10; ++i) {
if(i%2==1) {
x+=i;
}
else {
x--;
}
printf("%d, “ , x ) ;
}
printf("nx=%d“, x) ;
return 0;
}
i i%2==1 x (=0 initially) Output
1 T x=x+i=0+1=1 1,
2 F x--;
x=x-1=1-1=0
1, 0,
3 T x=x+i=0+3=3 1, 0, 3,

6. Problem
• Write a program to show the first n fibonacci
numbers.
1, 1, 2, 3, 5, 8, … … … , upto nth term

7. Solution
#include<stdio.h>
int main()
{
int prev1=1;
int prev2=1;
int n;
printf("Please enter the value of n: ");
scanf("%d",&n);
if(n==1) printf("%d",prev1);
else if(n>=2){
printf("%d, %d",prev1,prev2);
int cnt;
for(cnt=3;cnt<=n;cnt++){
int term=prev1+prev2;
printf(", %d",term);
prev1=prev2;
prev2=term;
}
}
return 0;
}

8. Solution using Array
#include<stdio.h>
int main()
{
int arr[1000];
arr[1]=1;
arr[2]=1;
int n;
printf("Please enter the value of n: ");
scanf("%d",&n);
if(n==1) printf("%d",arr[1]);
else if(n>=2){
int cnt;
for(cnt=3;cnt<=n;cnt++){
arr[cnt]=arr[cnt-1]+arr[cnt-2];
}
int i;
for(i=1;i<=n;i++){
printf("%d, ",arr[i]);
}
}
return 0;
}

9. Problem
• Write a program to find out the gcd between two
numbers.

10. Solution#include<stdio.h>
int main()
{
int num1,num2;
scanf("%d %d",&num1,&num2);
int mx,mn;
mx=(num1>num2)?num1:num2;
mn=(num1<num2)?num1:num2;
while(mx%mn!=0){
int rm=mx%mn;
mx=mn;
mn=rm;
}
printf("The GCD of %d and %d is %d",num1,num2,mn);
return 0;
}