我试图弄清楚为什么我会收到错误消息，从文件创建气泡排序。它可以是来自文件的任何文件，具体取决于我执行labcheck命令的时间。这已经到期了，但是我真的很想知道为什么。 C编程中的注释是CS讲师的指示。任何人都可以帮助修复C程序吗？
这是我进行实验室检查的时间：
p8.c: In function ‘main’:
p8.c:63:24: warning: format ‘%s’ expects a matching ‘char *’ argument [-Wformat=]
printf ("Usage: %s <file>\n");/*this should be followed as from
~^
p8.c:67:22: warning: implicit declaration of function ‘atof’; did you mean ‘feof’? [-Wimplicit-function-declaration]
char array[] = atof (argv[2]);
^~~~
feof
p8.c:67:22: error: invalid initializer
p8.c:68:18: warning: passing argument 1 of ‘bubblesort’ from incompatible pointer type [-Wincompatible-pointer-types]
bubblesort(array, 100);
^~~~~
p8.c:25:24: note: expected ‘char **’ but argument is of type ‘char *’
void bubblesort (char *A[], int n)
~~~~~~^~~
make: *** [Makefile:37: p8.o] Error 1
-4.0 p8 failed to compile.
这是我的代码分配：
/* 4 points */
#include <stdio.h>
#include <string.h>
#define MAXLEN 1000
/**
* Fill in the bubblesort function: https://en.wikipedia.org/wiki/Bubble_sort
* Using this pseudo-code, convert to C code:
* procedure bubbleSort( A : list of sortable items, n : length(A) )
* repeat
* newn = 0
* for i = 1 to n-1 inclusive do
* if A[i-1] > A[i] then
*
swap(A[i-1], A[i])
* newn = i
* end if
* end for
* n = newn
* until n <= 1
* end procedure
*/
void bubblesort (char *A[], int n)
{
int i, j, temp;
int length;
for (i = 0; i < length; i++)
{
for (j = 0; j < length - 1; j++)
{
if (*A[j + 1] < *A[j])
{
temp = *A[j];
*A[j] = *A[j + 1];
*A[j + 1] = temp;
}
}
}
}
/**
* Create a main function that opens a file composed of words, one per line
* and sorts them using the bubble-sort algorithm.
* Usage: "Usage: %s <file>\n"
* Example input/output:
* ./p8 testfile
* Bob
* Bubbles
* Butters
* Dave
* ...
*/
int main (int argc, char *argv[]) {
int rc, i;//rc is Read Character
if (argc < 2)
{
printf ("Usage: %s <file>\n");/*this should be followed as from
instruction, nothing can be change due to error message.*/
rc = -1;
} else {
char array[] = atof (argv[2]);
bubblesort(array, 100);
rc = 0;
while (rc < i)
{
printf ("%c\n", array[rc]);
rc++;
}
}
// prints print new lines from file
return 0;
}
答案 0 :(得分：2)
有很多错误。我创建了两个版本的代码。其中一个带有注释的错误。还有另一个清理工作的版本。
这是带注释的版本：
/* 4 points */
#include <stdio.h>
#include <string.h>
// NOTE/BUG: we need this for atof
#if 1
#include <stdlib.h>
#include <errno.h>
#endif
#define MAXLEN 1000
/**
* Fill in the bubblesort function: https://en.wikipedia.org/wiki/Bubble_sort
* Using this pseudo-code, convert to C code:
* procedure bubbleSort( A : list of sortable items, n : length(A) )
* repeat
* newn = 0
* for i = 1 to n-1 inclusive do
* if A[i-1] > A[i] then
*
swap(A[i-1], A[i])
* newn = i
* end if
* end for
* n = newn
* until n <= 1
* end procedure
*/
void
bubblesort(char *A[], int n)
{
int i,
j,
temp;
int length;
// NOTE/BUG: temp needs to be "char *temp"
// NOTE/BUG: "length" should be "n" here
// NOTE/BUG: replace all "*A[whatever]" with "A[whatever]"
for (i = 0; i < length; i++) {
for (j = 0; j < length - 1; j++) {
// NOTE/BUG: we need strcmp here
if (*A[j + 1] < *A[j]) {
temp = *A[j];
*A[j] = *A[j + 1];
*A[j + 1] = temp;
}
}
}
}
/**
* Create a main function that opens a file composed of words, one per line
* and sorts them using the bubble-sort algorithm.
* Usage: "Usage: %s <file>\n"
* Example input/output:
* ./p8 testfile
* Bob
* Bubbles
* Butters
* Dave
* ...
*/
int
main(int argc, char *argv[])
{
int rc,
i; // rc is Read Character
if (argc < 2) {
/* this should be followed as from instruction, nothing can be change due to
error message. */
// NOTE/BUG: this is missing the argv[0] argument
#if 0
printf("Usage: %s <file>\n");
#else
printf("Usage: %s <file>\n",argv[0]);
#endif
rc = -1;
}
else {
// NOTE/BUG: this is too short (i.e. it needs to be 100)
// NOTE/BUG: we need to read in the values
#if 0
char array[] = atof(argv[2]);
bubblesort(array, 100);
#else
char *array[100];
// NOTE/BUG: this should be argv[1]
FILE *fi = fopen(argv[2],"r");
if (fi == NULL) {
printf("unable to open '%s' -- %s\n",argv[2],strerror(errno));
exit(1);
}
int arrcnt = 0;
while (1) {
char buf[1000];
char *cp = fgets(buf,sizeof(buf),fi);
if (cp == NULL)
break;
cp = strchr(buf,'\n');
if (cp != NULL)
*cp = 0;
cp = strdup(cp);
array[arrcnt++] = cp;
}
fclose(fi);
bubblesort(array,arrcnt);
#endif
rc = 0;
while (rc < i) {
// NOTE/BUG: this should be "%s"
printf("%c\n", array[rc]);
rc++;
}
}
// prints print new lines from file
return 0;
}
这是清理后的工作版本：
/* 4 points */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <errno.h>
#define MAXLEN 1000
/**
* Fill in the bubblesort function: https://en.wikipedia.org/wiki/Bubble_sort
* Using this pseudo-code, convert to C code:
* procedure bubbleSort( A : list of sortable items, n : length(A) )
* repeat
* newn = 0
* for i = 1 to n-1 inclusive do
* if A[i-1] > A[i] then
*
swap(A[i-1], A[i])
* newn = i
* end if
* end for
* n = newn
* until n <= 1
* end procedure
*/
void
bubblesort(char *A[], int n)
{
int i, j;
char *temp;
for (i = 0; i < n; i++) {
for (j = 0; j < n - 1; j++) {
if (strcmp(A[j + 1],A[j]) < 0) {
temp = A[j];
A[j] = A[j + 1];
A[j + 1] = temp;
}
}
}
}
/**
* Create a main function that opens a file composed of words, one per line
* and sorts them using the bubble-sort algorithm.
* Usage: "Usage: %s <file>\n"
* Example input/output:
* ./p8 testfile
* Bob
* Bubbles
* Butters
* Dave
* ...
*/
int
main(int argc, char *argv[])
{
int rc = 0;
if (argc < 2) {
/* this should be followed as from instruction, nothing can be change
due to error message. */
printf("Usage: %s <file>\n",argv[0]);
rc = 1;
}
else {
char *array[100];
int arrmax = sizeof(array) / sizeof(array[0]);
FILE *fi = fopen(argv[1],"r");
if (fi == NULL) {
printf("unable to open '%s' -- %s\n",argv[1],strerror(errno));
exit(1);
}
int arrcnt = 0;
while (1) {
char buf[MAXLEN];
char *cp;
cp = fgets(buf,sizeof(buf),fi);
if (cp == NULL)
break;
if (arrcnt >= arrmax) {
printf("too many input lines\n");
exit(1);
}
cp = strchr(buf,'\n');
if (cp != NULL)
*cp = 0;
cp = strdup(buf);
array[arrcnt++] = cp;
}
fclose(fi);
bubblesort(array,arrcnt);
for (int arridx = 0; arridx < arrcnt; ++arridx)
printf("%s\n", array[arridx]);
}
// prints print new lines from file
return rc;
}