Program on Turbo C/C++

Program on Turbo C/C++

  • Submitted By: swaroop
  • Date Submitted: 02/20/2009 4:26 AM
  • Category: Technology
  • Words: 5486
  • Page: 22
  • Views: 538

C Questions

Note : All the programs are tested under Turbo C/C++ compilers.
It is assumed that,
➢ Programs run under DOS environment,
➢ The underlying machine is an x86 system,
➢ Program is compiled using Turbo C/C++ compiler.
The program output may depend on the information based on this assumptions (for example sizeof(int) == 2 may be assumed).

Predict the output or error(s) for the following:

1. void main()
int const * p=5;
Compiler error: Cannot modify a constant value.
p is a pointer to a "constant integer". But we tried to change the value of the "constant integer".

2. main()
char s[ ]="man";
int i;
for(i=0;s[ i ];i++)
printf("\n%c%c%c%c",s[ i ],*(s+i),*(i+s),i[s]);
s[i], *(i+s), *(s+i), i[s] are all different ways of expressing the same idea. Generally array name is the base address for that array. Here s is the base address. i is the index number/displacement from the base address. So, indirecting it with * is same as s[i]. i[s] may be surprising. But in the case of C it is same as s[i].

3. main()
float me = 1.1;
double you = 1.1;
printf("I love U");
printf("I hate U");
I hate U
For floating point numbers (float, double, long double) the values cannot be predicted exactly. Depending on the number of bytes, the precession with of the value represented varies. Float takes 4 bytes and long double takes 10 bytes. So float stores 0.9 with less precision than long double.
Rule of Thumb:
Never compare or at-least be cautious when using floating point numbers with relational operators (== , >, x);

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