C/C++ - Printf - ShareTechnote

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C/C++
printf()

As you know from "Hello World" program, you would know that printf() is a function to print out anything that you specified. It is very simple to use, but we often get confused by what kind of format we have to specify in order to get the right format that we want to get. The syntax is as simple as follows.

    int printf(const char *format, ...);

I would look very simple.. but you will see a long list of descriptions about '*format', but just reading throught the document would not help you much. I think the bunch of examples without much explanation would be bettern than long dry writing.

  • Printing Numbers in various format
  • printing very big numbers
  • Printing a number in binary format
  • printing a number in scientific format
Printing Numbers in various format

#include <stdio.h>

void main()

{

    int d = 123;

    float f = 123.45;

    printf("%d\n",d) ;

    printf("%8d\n",d) ;

    printf("%08d\n",d) ;

    printf("%x\n",d) ;

    printf("0x%x\n",d) ;

    printf("%#x\n",d) ;

    printf("0x%8x\n",d);

    printf("%#10x\n",d) ;

    printf("0x%08x\n",d) ;

    printf("%#010x\n",d) ;

    printf("%#X\n",d) ;

    printf("0x%8X\n",d) ;

    printf("%#10X\n",d) ;

    printf("0X%08X\n",d) ;

    printf("%#010X\n",d) ;

    printf("%f\n",f) ;

    printf("%8.2f\n",f) ;

    printf("%08.2f\n",f) ;

    printf("%8.3f\n",f) ;

    printf("%08.3f\n",f) ;

}

Result :------------------------------------

    printf("%d",d) ==>123

    printf("%8d",d) ==> 123

    printf("%08d",d) ==>00000123

    printf("%x",d) ==>7b

    printf("0x%x",d) ==>0x7b

    printf("%#x",d) ==>0x7b

    printf("0x%8x",d) ==>0x 7b

    printf("%#10x",d) ==> 0x7b

    printf("0x%08x",d) ==>0x0000007b

    printf("%#010x",d) ==>0x0000007b

    printf("%#X",d) ==>0X7B

    printf("0x%8X",d) ==>0x 7B

    printf("%#10X",d) ==> 0X7B

    printf("0X%08X",d) ==>0X0000007B

    printf("%#010X",d) ==>0X0000007B

    printf("%f",f) ==>123.449997

    printf("%8.2f",f) ==> 123.45

    printf("%08.2f",f) ==>00123.45

    printf("%8.3f",f) ==> 123.450

    printf("%08.3f",f) ==>0123.450

printing very big numbers

#include <stdio.h>

#include <stdlib.h>

int main()

{

long xLong = 2147483647;

long long xLongLong = 9223372036854775807;

printf("%d\n",xLong);

printf("%ld\n",xLong);

printf("\n");

printf("%d\n",xLongLong);

printf("%ld\n",xLongLong);

printf("%lld",xLongLong);

return(0);

}

Result :------------------------------------

    xLong in (%d) = 2147483647

    xLong in (%ld) = 2147483647

    xLongLong in (%d) = -1

    xLongLong in (%ld) = -1

    xLongLong in (%lld) = 9223372036854775807

printing a number in scientific format

#include <stdio.h>

#include <stdlib.h>

#include <math.h>

int main()

{

double xDouble = 2147483647.0;

printf("%f\n",xDouble);

printf("%e\n",xDouble);

printf("%E\n",xDouble);

printf("%g\n",xDouble);

printf("%G\n",xDouble);

return(0);

}

Result :------------------------------------

    xDouble in (%f) = 2147483647.000000

    xDouble in (%e) = 2.147484e+009

    xDouble in (%E) = 2.147484E+009

    xDouble in (%g) = 2.14748e+009

    xDouble in (%G) = 2.14748E+009

Printing a number in binary format

There is no printf option or any other functions to print a number in a binary format. So you need to create such a function on your own. Refer to Printing in a Binary Format example.

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