Common Input-Output Mistakes and Concepts in C

1.       printf(“sanjay”+2);   //prints njay only.

2.       Always use fflush(stdin) after any scanf statement.

3.       Always use & operator in scanf statement.

4.       We cannot use %d for inputting values other than int in scanf(for eg. long, float).

5.       Global variables initialize to 0, local to some garbage value. Global ‘char’ also initializes to 0.

6.       int/int is int. float/int is float. Int/float is float. (‘/’ represents division operator).

7.       scanf(“%c%c”,&ch1,&ch2);    //keyboard input must be ‘AB’ and not ‘A B’.

scanf(“%c %c”,&ch1,&ch2);  //keyboard input must be ‘A B’.

scanf(“%c/%c”,&ch1,&ch2);  //keyboard input must be ‘A/B’.

8.       printf returns the no. of bytes printed by it.

9.       scanf returns the no. of variables passed to it.

10.   sprintf(str, “%d %d”,x,y); // where str is a string.

sprintf does not prints on screen like printf, but it stores the formatted output in str.

Similarly sscanf takes the formatted input from str rather than from the keyboard.