Sorting 2 strings in array and merge them into one in C

Question

I am having troubles to finish my program i got some errors and i don't know what to d to fix them. My mission is to build a program that will get from the user 2 strings. i have to print them, then to sort them after that to make a function that will merge and sort with two strings into one. But if a name appears in the first string and second string then the third is the union of both is present in sorted order the two strings and display only once the name that will not be duplicates I guess it's about the malloc memory for the strings but i don't really know what to do!

1>c:\users\roni\documents\visual studio 2010\projects\lb11_12\lb11_12\lb_11_12_02.c(46): error C2106: '=' : left operand must be l-value
1>c:\users\roni\documents\visual studio 2010\projects\lb11_12\lb11_12\lb_11_12_02.c(47): error C2106: '=' : left operand must be l-value
========== Build: 0 succeeded, 1 failed, 0 up-to-date, 0 skipped ==========

this is my code:

#include <stdio.h>
#include <conio.h>
#include <string.h>
#include <stdlib.h>
#include <malloc.h>
#define LINES 4
#define length 100

void SortText1(char text1[LINES][length]);
void SortText2(char text2[LINES][length]);
void PrintStr1(char text1[LINES][length]);
void PrintStr2(char text2[LINES][length]);
void main ()
{
    int i;
    char text1[LINES][length];
    char text2[LINES][length];
    char text3[LINES+LINES][length];
    printf("First string,Please enter %d names (only capital letters,without spaces):", LINES);
    for ( i=0 ; i<LINES ; i++)
    {
        gets(text1[i]);
    }
    printf("Second string,Please enter %d names (only capital letters,without spaces):", LINES);
    for ( i=0 ; i<LINES ; i++)
    {
        gets(text2[i]);
    }
    PrintStr1(text1);
    PrintStr2(text2);
    SortText1(text1);
    system("pause");
    return ;
}
void SortText1(char text1[LINES][length])
{

    int i,j,k;
    for (i=LINES-1 ; i>0 ; i--)
    {
        for ( j=0 ; j<i ; j++ )
        {
            if(strcmp(text1[i],text1[i+1]) > 0 )
            {
                char *temp=text1[i+1];
                text1[i+1]=text1[i];
                text1[i]=temp;
            }
        }
    }
    printf("The first string sorted:\n");
    for ( k=0 ; i<LINES ; k++)
        {
            printf("%s ",text1[k]);
        }
    printf("\n");
}
void PrintStr1(char text1[LINES][length])
{
    int i;
    printf("The first string of NAMES:\n");
    for ( i=0 ; i<LINES ; i++)
        {
            printf("%s ",text1[i]);
        }
    printf("\n");
}
void PrintStr2(char text2[LINES][length])
{
    int i;
    printf("The second string of NAMES:\n");
    for ( i=0 ; i<LINES ; i++)
        {
            printf("%s ",text2[i]);
        }
    printf("\n");
}

Which lines are 46 and 47 (the ones mentioned in the errors)? — Some programmer dude
– Some programmer dude, Commented Sep 19, 2013 at 16:42

P0W · Accepted Answer · 2013-09-19 16:48:24Z

2

You need to use strcpy function to copy string

Fix Line No. 45 & 46

    if(strcmp(text1[i],text1[i+1]) > 0 )
    {
        char *temp= malloc(sizeof(char)*strlen(text1[i+1])+1);
        strcpy(temp,text1[i+1]);
        strcpy(text1[i+1],text1[i]); // Line No. 45
        strcpy(text1[i],temp); //Line No. 46
        free(temp);
    }

edited Sep 19, 2013 at 16:48

answered Sep 19, 2013 at 16:42

P0W

48.1k9 gold badges78 silver badges124 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Some programmer dude Over a year ago

No need to dnyamically allocate temp, as the source is never going to be longer than length character you can just declare it as a normal array or length characters.

AndersK · Accepted Answer · 2013-09-19 16:51:32Z

0

You will not be able to sort it like that since you have a 2-dim array so this code is not correct for that purpose

if(strcmp(text1[i],text1[i+1]) > 0 )
{
  char *temp=text1[i+1];
  text1[i+1]=text1[i];
  text1[i]=temp;
}

if you want to swap two arrays with another you need to physically copy the characters from one array to the other e.g. strncpy.

A more effective way is to create an array of pointers to strings and then swap the pointers.

char *text1[SIZE];
for (i = 0; i < SIZE; ++i)
  text1[i] = malloc(length);

...

fgets( text1[i], length, stdin );

...

then your swap functionality would work

if(strcmp(text1[i],text1[i+1]) > 0 )
{
  char *temp=text1[i+1];  
  text1[i+1]=text1[i];     
  text1[i]=temp;
}

answered Sep 19, 2013 at 16:51

AndersK

36.1k6 gold badges63 silver badges86 bronze badges

3 Comments

Sagi Binder Over a year ago

Hey claptrap what does fgets means? In the main I should do it after i create the array?

Sagi Binder Over a year ago

Sorry for my ignorance. Newcomer I'd appreciate it if you show me the boot memory for the array and a pointer definition

AndersK Over a year ago

fgets is safer than gets which does not give you a possibility to tell a max size of the buffer so with gets you could potentially enter a too long string and then get an error.

JeremyP · Accepted Answer · 2013-09-19 16:52:27Z

0

You need to understand what an lvalue is. It's quite an important concept in C.

Basically, an lvalue is a value you can assign a value to, like a variable.

This line:

text1[i+1]=text1[i]

tries to assign a whole row of values at once. text1[i + 1] is not an lvalue so the statement is illegal.

It's better to define your data structures as arrays of strings (char*) e.g.

char* text1[LINES];

But you do need to do a bit more set up to allocate and initialise the memory.

answered Sep 19, 2013 at 16:52

JeremyP

87.4k15 gold badges129 silver badges164 bronze badges

2 Comments

Sagi Binder Over a year ago

Sorry for my ignorance. Newcomer I'd appreciate it if you show me the boot memory for the array and a pointer definition

Sagi Binder Over a year ago

I am still getting errors while i trying to set up memory allocte in the main.void main () { int i; char text1[LINES][length]; char text2[LINES][length]; char text3[LINES+LINES][length]; printf("First string,Please enter %d names (only capital letters,without spaces):", LINES); for ( i=0 ; i<LINES ; i++) { gets(text1[i]); } for (i = 0; i<LINES ; i++) { text1[i]=(char )malloc(lengthsizeof(char)); }

Collectives™ on Stack Overflow

Sorting 2 strings in array and merge them into one in C

3 Answers 3

1 Comment

3 Comments

2 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

3 Comments

2 Comments

Your Answer

Sign up or log in

Post as a guest

Related