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Question

Can you please help me with merging of two texts into one using just only stdio.h and stdlib.h ? The result should be HelloWorld .

So far, I have the following, but there is a mistake somewhere.

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

char *spojeni(char *t1, char *t2)
{
    char pole_spolecne[10];
    for (*t1 = 0; *t1 < 5; t1++)
    {
        pole_spolecne[*t1] = *t1;
    }

    for (*t2 = 0; *t2 < 10; t2++)
    {
        pole_spolecne[*t2 + 5] = *t2;
    }

    return pole_spolecne;
}

int main()
{
    char pole1[] = { "Hello" };
    char pole2[] = { "World" };



    printf("%s\n", spojeni(pole1, pole2));

    system("pause");
    return 0;
}

My new solution, but it returns an error at the end:

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <stdlib.h>

char *spojeni(char *t1, char *t2)
{
    char pole_cele[20];
    char *p_pole_cele;
    p_pole_cele = t1;
    strcat(p_pole_cele, t2);

    return p_pole_cele;
}

int main()
{
    char pole1[] = { "Hello" };
    char pole2[] = { "World" };

    char *p_pole1;
    char *p_pole2;

    p_pole1 = pole1;
    p_pole2 = pole2;


    printf("%s\n)", spojeni(p_pole1, p_pole2));


    system("pause");
    return 0;
}

Finally, this change of function helped: char *spojeni(char *t1, char *t2)

{
    char pole_cele[20];
    char *p_pole_cele;
    p_pole_cele = (char *)malloc(10);
    strcpy(p_pole_cele, t1);
    p_pole_cele = (char *)realloc(p_pole_cele, 20);
    strcat(p_pole_cele, t2);

    return p_pole_cele;
}

Answer 1

I am not quite sure how to answer this, as this is clearly a teaching exercise, and, to be blunt, the code given shows a lack of understanding of pointers. And pointers is a topic better taught in person than via a web-site comment.

A few hints, though:

• Think very clearly about pointers, what they are pointing to, and what makes them different from array indices.

• Draw diagrams to visualize what you're doing.

• Your exercise can be solved using calloc(), strlen() and strcpy().