Why union doesn't work properly but struct does?

Debojit Acharjee 435 Reputation points

In the following program the values of the variable "orange" is printed properly when "union" is changed to "struct", but why the int and float values don't print properly when "union" is used?

#include <stdio.h>

union fruit
  int number;
  float weight;
  char *color;
} orange;
int main()
  orange.number = 6;
  orange.weight = 1.3;
  orange.color = "orange";

  printf("There are %d %s colored oranges weighing %.2f pounds", orange.number, orange.color, orange.weight);

  return 0;


There are 4214884 orange colored oranges weighing 0.00 pounds

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An object-oriented and type-safe programming language that has its roots in the C family of languages and includes support for component-oriented programming.
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A high-level, general-purpose programming language, created as an extension of the C programming language, that has object-oriented, generic, and functional features in addition to facilities for low-level memory manipulation.
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Accepted answer
  1. Bruce (SqlWork.com) 61,026 Reputation points

    The union uses the same address for all the properties. This allows the same address to be interpreted as different types. A union will always be the value of the last assignment. In your case the literal.”orange”. When seen as a int, it’s the address, when seen as a float, it’s the address bits as a float.

    note. The sizeof of a union is the size of the largest property.

    1 person found this answer helpful.

1 additional answer

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  1. David Lowndes 4,711 Reputation points

    You need to read up on what a union is.

    3 people found this answer helpful.