73 lines
2.1 KiB
C
73 lines
2.1 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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union number
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{
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double d;
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float f;
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long l;
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int i;
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unsigned short s;
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unsigned char c[8];
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};
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int main(void)
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{
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/* Define variables and a union */
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int my_i;
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short my_s;
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unsigned char tc;
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union number mynum;
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/* Prompt for use input ao a number whose bytes we are to swap */
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printf ("\nPlease enter a number ");
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scanf("%hi",&my_s); // hi is the format for a signed short
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/* pop this number into our union */
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mynum.s = my_s;
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/* Show the present byte order */
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printf ("\nThe bytes making up your number %hi are ",my_s);
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printf ("%d %d %d %d %d %d %d %d ",mynum.c[0],mynum.c[1],mynum.c[2],mynum.c[3],mynum.c[4],mynum.c[5],mynum.c[6],mynum.c[7]);
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/* We now swap the two lowest bytes (via an intermediate variable) */
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tc = mynum.c[1];
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mynum.c[1] = mynum.c[0];
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mynum.c[0] = tc;
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printf ("\nThe bytes making up your number are now ");
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printf ("%d %d %d %d %d %d %d %d ",mynum.c[0],mynum.c[1],mynum.c[2],mynum.c[3],mynum.c[4],mynum.c[5],mynum.c[6],mynum.c[7]);
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printf ("\nWhich corresponds to %d ",mynum.s);
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// Repeat for an integer
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/* Prompt for use input ao a number whose bytes we are to swap */
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printf ("\nPlease enter a number [INTEGER] ");
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scanf("%d",&my_i);
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/* pop this number into our union */
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mynum.i = my_i;
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/* Show the present byte order */
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printf ("\nThe bytes making up your number %d are ",my_i);
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printf ("%d %d %d %d %d %d %d %d ",mynum.c[0],mynum.c[1],mynum.c[2],mynum.c[3],mynum.c[4],mynum.c[5],mynum.c[6],mynum.c[7]);
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/* We now swap the 1st and 4th bytes (via an intermediate variable) */
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tc = mynum.c[3];
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mynum.c[3] = mynum.c[0];
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mynum.c[0] = tc;
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/* We now swap the 1st and 4th bytes (via an intermediate variable) */
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tc = mynum.c[2];
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mynum.c[2] = mynum.c[1];
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mynum.c[1] = tc;
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printf ("\nThe bytes making up your number are now ");
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printf ("%d %d %d %d %d %d %d %d ",mynum.c[0],mynum.c[1],mynum.c[2],mynum.c[3],mynum.c[4],mynum.c[5],mynum.c[6],mynum.c[7]);
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printf ("\nWhich corresponds to %d ",mynum.i);
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return 0;
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}
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