Exercise 5-5. Write versions of the library functions strncpy, strncat, and strncmp, which operate on at most the first n characters of their argument strings. For example, strncpy(s,t,n) copies at most n characters of t to s. See the description in Appendix B. Three functions, each with a character count limit n. The non-obvious behaviour …
Exercise 5-4. Write the function strend(s,t), which returns 1 if the string t occurs at the end of the string s, and zero otherwise. Advance both pointers to their respective null terminators, then walk backwards together comparing characters. If t runs out first (pointer reaches the start of t), every character matched — t is …
Exercise 5-3. Write a pointer version of the function strcat that we showed in Chapter 2: strcat(s,t) copies the string t to the end of s. The Chapter 2 version used array indexing with integer subscripts. The pointer version eliminates the index variables entirely: advance s to its null terminator, then copy t character-by-character (including …
Exercise 5-2. Write getfloat, the floating-point analog of getint. What type does getfloat return as its function value? getfloat returns int — the same as getint. This might seem surprising since it reads a double. The return value is used as a status indicator: it returns the terminating non-numeric character (so the caller can check …
Exercise 5-1. As written, getint treats a + or – not followed by a digit as a valid representation of zero. Fix getint so that it pushes such a character back on the input. K&R’s getint from Section 5.2 reads an optional sign then digits. The bug: if + or – appears but the next …
Exercise 4-14. Define a macro swap(t,x,y) that interchanges two arguments of type t. (Block structure will help.) A three-argument swap macro: t is the type, x and y are the variables to swap. The block { … } creates a local scope for the temporary, preventing name leakage. The conventional temp variable name _swap_tmp (with …