/* Write a function reverse(s) that reverses the character string s. Use it to
write a program that reverses its input a line at a time. */
#include <stdio.h>
#define MAXLINE 1000 /* maximum input line size */
int getline(char line[], int maxline);
int reverse(char s[]);
/* reverse input lines, a line at a time */
main()
{
char line[MAXLINE]; /* current input line */
while((getline(line, MAXLINE)) > 0)
{
reverse(line);
printf("%s", line);
}
}
/* getline: read a line into s, return length */
int getline(char s[], int lim)
{
int c, i, j;
j = 0;
for(i = 0; (c = getchar()) != EOF && c != '\n'; ++i)
{
if(i < lim - 2)
{
s[j] = c; /* line still in boundaries */
++j;
}
}
if(c == '\n')
{
s[j] = c;
++j;
++i;
}
s[j] = '\0';
return i;
}
/* reverse: reverse string s */
void reverse(char s[])
{
int i, j;
char temp;
i = 0;
while(s[i] != '\0') /* find the end of string s */
{
++i;
}
--i; /* back off from '\0' */
if(s[i] == '\n')
{
--i; /* leave newline in place */
}
j = 0; /* beginning of new string s */
while(j < i)
{
temp = s[j];
s[j] = s[i]; /* swap the characters */
s[i] = temp;
--i;
++j;
}
}
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C - The C Answer (2nd Edition) - Exercise 1-19
原文地址：http://blog.csdn.net/troubleshooter/article/details/47092143
