C- sort array alphabetically from stdin [closed] - c

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I have to make a program in C which reads input from standard input and writes on the screen, strings order alphabetically. Can you please help me?
Here is the program:
#include <stdio.h>
#include <string.h>
int main (int argc, char *argv[])
{
char tabela[100][50];
int i=0;
int j,k;
char string[50];
char temp[50];
while(fgets(string,sizeof(string), stdin) != NULL)
{j=0;
while(j<strlen(string)){
tabela[i][j]=string[j++];
}
i++;
}
for(j=0; j < i ; j++){
for(k=j+1; k< i; k++)
{
if(strcmp(tabela[j],tabela[k]) > 0)
{
strcpy(temp,tabela[j]);
strcpy(tabela[j],tabela[j]);
strcpy(tabela[k],temp);
}
}
}
for (j = 0; j <i; j++){
printf("%s\n", tabela[j]);
}
// sort(tabela,i);
/* for(k = 0; k <=i;k++){
printf("\n");
for(j = 0; j <=i;j++) {
printf("%c", tabela[j][k]);
} //for */
/*
}//for */
return 0;
}//main
Thanks

Answer 1

One opportunity is, to run through a selection sort:
/* selection sort */
void sort(char **a, int n) {
int min, i, j;
char t[50];
for (i = 0; i < n; i++)
{
min = i;
for (j = i+1; j < n; j++)
{
if (strcmp(a[j],a[min]) < 0) min = j;
}
strcpy(t,a[min]);
strcpy(a[min],a[i]);
strcpy(a[i],t);
}
}

Answer 2

C/C++ provides a library for sorting in stdlib.h called "qsort" (quicksort) here
If you need an example:
Basically, you will need to include the required library "stdlib.h" and "string.h" first, then you will need to define a comparison function.
int cmp(const void* a, const void* b)
{
int arg0 = *(char*) a, arg1 = *(char*)b;
return arg0-arg1;
}
Supposed that you have a char array of length 100.
char example[100] = "adfasdfasdfsdasdfasdfafhtyjytjukvr";
Then you call the function qsort like this:
qsort(example,strlen(example),sizeof(char),cmp);
There you go :)
Alternatively, in C++, there are another built-in sorting functions std::sort() and std::stable_sort() available in the header <algorithm> which can not only work with your char array, but also other C++ containers. You may call it like this:
std::sort(example,example+strlen(example));
Further reading:
C++ containers
C++ sort
C++ stable sort

Answer 3

I presume this is an exercise in writing sorting code, so (to avoid doing your homework for you) I'll stick with general suggestions, based on sorting exercises and real-world sorts I've written.
Sorting a list during input from console begs for an insertion sort -- that is, sorting is done as the list is input, so that a "very short time" after pressing ENTER for each entry, the list is fully sorted (ideally, short enough the user can't tell anything was done before the next entry prompt is presented). Sorting with large list elements can be very time consuming, hence the common use of tag sorts (where you sort tags instead of the actual list elements), but it's unlikely you'll have that level of element size from manual entry. A very long list can give similar problems (depending on the efficiency of the search algorithm), but again, that's a problem limited by the entry method.
With your list limited (by array declaration) to 100 elements no more than 50 characters long, the user would never notice the delay if you used a simple step-through test and wholesale move-down for elements that need to be after the new element (on a modern computer, the sort steps after insertion wouldn't exceed a few milliseconds execution time even in an interpreting language), but (on the assumption you're learning something that will be of use later for larger programs and data sets) it's far more efficient to use a binary tree search and linked list; you could get that kind of insertion time for a list of thousands of elements each thousands of bytes long if you only have to look at a tiny fraction of them and never have to move any of them, but only shuffle integers in a tag array.