Write a small fragment of code that shows how unions can be used in C to interpr

Question

Write a small fragment of code that shows how unions can be used in C to interpret the bits of a value of one type as if they represented a value of some other type (non-converting type cast).

What is this question asking? Can anyone explain? Thank you.

The following graph is what I find in my textbook.

1.6 Non converting casts C programmers sometimes attempt a nonconverting type cast (type pun) by taking the address of an object, converting the type of the resulting pointer and then dereferencing: r *((float &n;) This arcane bit of hackery usually incurs no run-time cost, because most (but not all!) implementations use the same representation for pointers to integers and pointers to floating-point values-namely, an address. The ampersand operator (&) means "address of," or "pointer to." The parenthesized (float is the type name for "pointer to float" (float is a built-in floating-point type) The prefix operator is a pointer dereference. The overall construct causes the compiler to interpret the bits of n as if it were a float. The reinterpretation will succeed only if n is an l-value (has an address), and ints and floats have the same size (again, this second condition is often but not always true in C). If n does not have an address then the compiler will announce a static semantic error. If int and float do not occupy the same number of bytes, then the effect of the cast may depend on a variety of factors, including the relative size of the objects, the alignment and "endian-ness" of memory (Section C-5.2), and the choices the compiler has made regarding what to place in adjacent locations in memory. Safer and more portable n casts can be achieved in C by means of unions variant records); we consider this option in Exercise C-8.24

Explanation / Answer

#include <stdio.h> #include <string.h> union student {             char name[20];             char subject[20];             float percentage; }record; int main() {             strcpy(record.name, "Raju");             strcpy(record.subject, "Maths");             record.percentage = 86.50;             printf(" Name       : %s ", record.name);             printf(" Subject    : %s ", record.subject);             printf(" Percentage : %f ", record.percentage);             return 0; } #include <stdio.h> #include <string.h> union student {             char name[20];             char subject[20];             float percentage; }record; int main() {             strcpy(record.name, "Raju");             strcpy(record.subject, "Maths");             record.percentage = 86.50;             printf(" Name       : %s ", record.name);             printf(" Subject    : %s ", record.subject);             printf(" Percentage : %f ", record.percentage);             return 0; } #include <stdio.h> #include <string.h> union student {             char name[20];             char subject[20];             float percentage; }record; int main() {             strcpy(record.name, "Raju");             strcpy(record.subject, "Maths");             record.percentage = 86.50;             printf(" Name       : %s ", record.name);             printf(" Subject    : %s ", record.subject);             printf(" Percentage : %f ", record.percentage);             return 0; }

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