Data Input and Output-III

Little More about printf
Flags in printf function:

• We can place flags in the printf statement with in the control string which will affect the appearance of the output.
• The flag must be placed immediately after the percent sign(%).
• Two or flags can be combined for a single output.
• Table shows the commonly used flags
  
  
  

  Flag	Meaning
  -	Data item is left justified(ie)Blanks added after the data item
  +	A sign(+(or)-) will precede with each signed numerical data item
  0	Place leading zeros to appear instead of leading blanks
  #(with 0- & x- type conversion)	Causes octal and hexadecimal data items to be processed by 0 and 0x respectively
  #(with e-,f- & g- type conversion)	Causes a decimal point to be present in all floating point numbers even if the data item is a whole number.Also prevents the truncation of trailing zeros in g-type conversion

• Example:
  
  
  
   
   

  #include<stdio.h> int main() {     int x=1234;     float y=15.5,z=-5.5;     printf("%d %f %e\n",x,y,z);     printf("%6d %7.0f %10.1e\n",x,y,z);     printf("%-6d %-7.0f %-10.1e\n",x,y,z);     printf("%+6d %+7.0f %+10.1e\n",x,y,z);     printf("%-+6d %-+7.0f %-+10.1e\n",x,y,z);     printf("%7.0f %#7.0f %7g %#7g\n",y,y,z,z);     return 0; }

  
  OutPut:
  
  
  

  1234 15.500000 -5.500000e+00   1234      16   -5.5e+00 1234   16      -5.5e+00   +1234     +16   -5.5e+00 +1234  +16     -5.5e+00       16     16.    -5.5 -5.50000

Prefixes in printf function: 

• Prefixes within the control string to indicate the length of the corresponding argument.
• Example: i indicates a signed or unsigned integer argument or a double precision argument. h indicates signed or unsigned short integer.
  
  

  #include<stdio.h> int main() {     short x,y;     long a,b;     printf("%5hd %6hx %8lo %lu\n",x,y,a,b);     return(0); }

  hd->short decimal integer
  hx->short hexadecimal integer
  lo->Long octal integer
  lu->Long unsigned integer
• It is also possible to write the conversion characters x,e,g in uppercase as X,E,G. These uppercase conversion characters cause any letters with in the output data to be displayed in uppercase
  Example:
  
  

  #include<stdio.h> int main() {     int x=0x10ab,y=0777;     float z=0.3e-12;     printf("|%8x %10.2e|\n",x,z);     printf("|%8X %10.2E|\n",x,z);     printf("|%8x %8o|\n",x,y);     printf("|%#8x %#8o|\n",x,y);     return(0); }

  Output:
  
  

  | 10ab 3.00e-13| | 10AB 3.00E-13| | 10ab 777| | 0x10ab 0777|

gets() and puts() Function:

• gets and puts function used to read and write string(character array terminate with a newline character)
• The string may include whitespace characters
• Example:
  
  

  #include<stdio.h> int main() {     char text[100];     gets(text);     puts(text);     return(0); }

  
  Output:
  ./a.out
  helo welcome
  helo welcome