"The C Programming Language", 2nd edition, Kernighan and Ritchie

Answers to Exercises

Chapter 3 - Control Flow

Ex No Pg No Exercise Solution Solved by
1 58 Our binary search makes two tests inside the loop, when one would suffice (at the price of more tests outside). Write a version with only one test inside the loop and measure the difference in run-time. Listing krx301 Paul Griffiths, Colin Barker, Andrew Tesker
2 60 Write a function escape(s,t) that converts characters like newline and tab into visible escape sequences like \n and \t as it copies the string t to s . Use a switch . Write a function for the other direction as well, converting escape sequences into the real characters. Listing krx302 Paul Griffiths
3 63 Write a function expand(s1,s2) that expands shorthand notations like a-z in the string s1 into the equivalent complete list abc...xyz in s2 . Allow for letters of either case and digits, and be prepared to handle cases like a-b-c and a-z0-9 and -a-z . Arrange that a leading or trailing - is taken literally. Listing krx303 Paul Griffiths
4 64 In a two's complement number representation, our version of itoa does not handle the largest negative number, that is, the value of n equal to -(2 to the power (wordsize - 1)) . Explain why not. Modify it to print that value correctly regardless of the machine on which it runs. Listing krx304 Paul Griffiths
5 64 Write the function itob(n,s,b) that converts the integer n into a base b character representation in the string s . In particular, itob(n,s,16) formats n as a hexadecimal integer in s . Listing krx305 Paul Griffiths
6 64 Write a version of itoa that accepts three arguments instead of two. The third argument is a minimum field width; the converted number must be padded with blanks on the left if necessary to make it wide enough. Listing krx306 Paul Griffiths


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