I have a program, that asks several strings and should sort them. My code is:
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#define MAX_STR_LEN 256
int myStrCmp (const void * a, const void * b)
{
return strcmp((const char *)a, (const char *)b);
}
int main(void)
{
int strNum; // expected number of input strings
int strCnt; // counter of strings
char ** storage; // pointr to the memory when strings are stored
char strBuf[ MAX_STR_LEN]; // buffer for strings
char * strPtr;
// input of strings number
do{
printf("How many strings will be entered: ");
while( scanf("%d", &strNum) != 1)
{
printf("ERROR: Not number was entered!\n");
while( getchar() != '\n' );
printf("Please enter a number: ");
}
if( strNum < 2 )
{
printf("ERROR: Number less than 2 was entered!\n");
}
while( getchar() != '\n' );
}
while(strNum < 2);
// allocation of memory for pointers
storage = (char **) calloc(strNum, sizeof(char*) );
if( storage == NULL )
{
printf("ERROR: Unexpected problems with memory allocation!\n");
return 1;
}
// input of strings
for( strCnt = 0; strCnt < strNum; strCnt++)
{
printf("Enter string #%d:\n", strCnt + 1);
fgets(strBuf, MAX_STR_LEN, stdin);
strPtr = strchr(strBuf, '\n');
if( strPtr )
{
*strPtr = '\0';
}
else
{
strBuf[ MAX_STR_LEN - 1] = '\0';
}
// allocation memory for particular string
storage[strCnt] = (char *) malloc(strlen(strBuf) + 1);
if(storage[strCnt] == NULL)
{
printf("ERROR: Unexpected problems with memory allocation!\n");
return 2;
}
// move string to dynamic memory
strcpy(storage[strCnt], strBuf);
}
// sort the strings
qsort(storage, strNum, sizeof(char**), myStrCmp);
// output the result
printf("\nSorted strings:\n");
for( strCnt = 0; strCnt < strNum; strCnt++)
{
printf("%s\n", storage[strCnt]);
}
return 0;
}
The simplest test shows the trouble:
How many strings will be entered: 3
Enter string #1:
ddd
Enter string #2:
aaa
Enter string #3:
ccc
Sorted strings:
ddd
aaa
ccc
I have tryed Visual C++ and gcc, but the result is the same. Please, say me what is wrong in the code?
qsort(). You could go in there and just hardcode it such thatstorageis always the same 5 strings. That would make your question awesome!storage = (char **) calloc(strNum, sizeof(char*) );, considerstorage = calloc(strNum, sizeof *storage);Easier to code and maintain.