在学习 Brian W. Kernighan 和 Dennis M. Ritchie 的 C 编程语言时,我尝试了 1.9 节字符数组中的示例。以下是代码:
/* read a set of text lines and print the longest */
#include <stdio.h>
#define MAXLINE 1000 /* maximum input line length */
/* declare functions: getline() and copy() */
int getline(char line[], int maxline);
void copy(char to[], char from[]);
/* getline: read a line into array "s", return length */
int getline(char s[], int lim)
{
int c, i;
for (i=0; i < lim-1 && (c=getchar())!=EOF && c!='\n'; ++i)
s[i] = c;
if (c == "\n"){
s[i] = c;
++i;
}
s[i] = '\0'; /* the null character whose value is 0 */
return i;
}
/* copy: copy 'from' into 'to'; assume to is big enough */
/* the return type of copy is "void" -- no value is returned */
void copy(char to[], char from[])
{
int i;
i = 0;
while ((to[i] = from[i]) != '\0') /* terminated with a \0 */
++i;
}
/* print the longest input line */
int main()
{
int len; /* current line length */
int max; /* maximum length seen so far */
char line[MAXLINE]; /* current input line */
char longest[MAXLINE]; /* longest line saved here */
max = 0;
while ((len = getline(line, MAXLINE)) > 0)
if (len > max) {
max = len;
copy(longest, line);
}
if (max>0) /* there was a line */
printf("%s", longest);
return 0;
}
有两个主要错误:
- 错误:“getline”的类型冲突</li>
- 错误:“getline”的先前声明在这里
完整的错误列表在这里:
/Users/C/Codes/Ritchie/array_char.c:8: error: conflicting types for ‘getline’
/usr/include/stdio.h:449: error: previous declaration of ‘getline’ was here
/Users/C/Codes/Ritchie/array_char.c:13: error: conflicting types for ‘getline’
/usr/include/stdio.h:449: error: previous declaration of ‘getline’ was here
/Users/C/Codes/Ritchie/array_char.c: In function ‘getline’:
/Users//C/Codes/Ritchie/array_char.c:17: warning: comparison between pointer and integer
/Users/C/Codes/Ritchie/array_char.c:17: warning: comparison with string literal results in unspecified behavior
我不确定出了什么问题,因为它与书中的代码完全相同。也许在开头的函数声明:
int getline(char line[], int maxline);
void copy(char to[], char from[]);
有问题吗?谢谢!