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PHY225 TURN OVER
DEPARTMENT OF PHYSICS AND ASTRONOMY
Autumn Semester 2011-
PROGRAMMING IN C 2 HOURS
Answer ALL questions
There are a total of 50 marks to be awarded for this paper. The breakdown on the right-hand side of the paper is meant as a guide to the marks that can be obtained from each part of the question.
Please write all answers to questions in your answer booklet and not on the examination paper.
PHY225 CONTINUED
- a) Explain the concept of linking in the creation of an executable file. What external files may be required during the linking process?
b) What is a relational operator? Give an example of one.
c) What is the purpose of a function prototype?
d) In the statement int main(void) what does (void) signify?
e) How does the atan2() function differ from the atan() function?
f) What does the strcmp() function do?
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[1]
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- Study the following program and predict the values of r, s, t, u , k , l and m to the same precision as specified in the printf statements:
#include <stdio.h> #include <stdlib.h>
int main(void) { double r=333.45,s=3.4e-2,t=1.008,u=152.5; int i=34,j=-34,k=808,l=5034 2 ,m=0;
r = (t+r*s/u-u/r); s = s+u/t+r/t-r; t = --u; u = sqrt(abs(r-t/s)); k = (i/j)u; l += k-(i%l)j; m *= i;
printf (“r: %f s: %f t: %f u: %f\n”,r,s,t,u); printf (“k: %d l: %d m: %d\n”,k,l,m);
system(“pause”); return 0; }
[8]
PHY225 CONTINUED
- Study the following program and write out exactly what is written out at the printf statement:
#include<stdlib.h> #include<stdio.h>
int main(void) { int i=9, j=1; while (i>0) { if (i%3) { j+=i; j*=i; i--; } else if (i%5) i--; i--; printf("i: %d j: %d\n",i,j); }
system("pause"); return 0; }
[7]
PHY225 TURN OVER
- Ben works for British Gas and is writing a computer program to read customer records from a database into an array of structures. Each customer record comprises the following information:
CustomerSurname (character string, maximum 20 characters) CustomerNumber (integer, up to 10 digits) CurrentMeterReading (integer, up to 6 digits) LastBill (amount in pounds and pence)
A typical customer record would thus look like:
Brown 4382910395 001789 142.
Ben’s program is incomplete. So far it looks like this:
#include<stdlib.h> #include<stdio.h> #include<math.h>
//TODO I need to define my structure here
int main(void)
{ int NUM_CUSTOMERS; printf(“Enter the number of customers:”); scanf(“%d”,NUM_CUSTOMERS);
//TODO I need to define my array of structures here
FILE* database;
if((database = fopen("customers.db", "r"))==NULL) { printf("Could not open database file”); return 1; }
for(i=0; i<NUM_CUSTOMERS; ++i) {
//TODO This is where my fscanf command goes
} fclose(database); system(“pause”); return(0);
}
PHY225 TURN OVER
END OF EXAMINATION PAPER
