what am i doing wrong?

newbiecr · 11-04-2009, 12:01 PM

im trying to calculate the sum of 1/1 + 1/2+...+1/100

Code:

#include <stdio.h>
int main() {
    
    int i;
    
    float res;
    
    res = 0;
    
    for (i=1;i<=100;i++){

        res = res + 1/i;
       
        }

    printf("%f",res);
    
    getchar();
    
    return 0;
    
}

result: 1????????????????????

Adak · 11-04-2009, 12:04 PM

You're doing integer division, where the remainder is thrown out, so it boils down to 1/1 = 1, and all the other divisions are zero's.

So the answer is just 1.

newbiecr · 11-04-2009, 12:07 PM

Quote:

Originally Posted by Adak

You're doing integer division, where the remainder is thrown out, so it boils down to 1/1 = 1, and all the other divisions are zero's.

So the answer is just 1.

thank you i changed to

Code:

#include <stdio.h>
#include <math.h>
int main() {
    
    int i;
    
    float res;
    
    res = 0;
    
    for (i=1;i<=100;i++){

        res = res + 1.0/i;
       
        }

    printf("%f",res);
    
    getchar();
    
    return 0;
    
}

and i think it works now

result: 5.187378

is it correct?

Kennedy · 11-04-2009, 12:12 PM

Usually, it is best to define the types in the code:

res = res + 1.0f/(float)i;

Though this is not a requirement.

Elysia · 11-04-2009, 01:11 PM

Only one side needs to be a floating point, though.

11-04-2009, 12:01 PM	#1
newbiecr Registered User Join Date: Nov 2009 Posts: 3	what am i doing wrong? im trying to calculate the sum of 1/1 + 1/2+...+1/100 Code: #include <stdio.h> int main() { int i; float res; res = 0; for (i=1;i<=100;i++){ res = res + 1/i; } printf("%f",res); getchar(); return 0; } result: 1????????????????????
newbiecr is offline

11-04-2009, 12:04 PM	#2
Adak Registered User Join Date: Sep 2006 Posts: 2,517	You're doing integer division, where the remainder is thrown out, so it boils down to 1/1 = 1, and all the other divisions are zero's. So the answer is just 1.
Adak is offline

11-04-2009, 12:12 PM	#4
Kennedy Jaxom's & Imriel's Dad Join Date: Aug 2006 Location: Alabama Posts: 801	Usually, it is best to define the types in the code: res = res + 1.0f/(float)i; Though this is not a requirement.
Kennedy is offline

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