CODEWITHSUNDEEP
cstringpointers
XJZ
XJZ

Reputation: 47

What is the difference between two ways to manipulate strings in C?

I want to copy a string "str" to p . First I used the code I commented out, but the output was empty. So I tried the code that is below the commented area, and it worked. What is the difference between the two methods to manipulate strings in C? Thanks in advance.

    #include <stdio.h>
    #include <string.h>
    #include <stdlib.h>

    int main(void)
    {
        char *str = "laekfja";
        char *p = (char*)malloc(51 * sizeof(char));

        //First try.
        /*  while(*str)             
                {                   
                    *p++ = *str++;  
                }                   
            *p = '\0';
            printf("%s\n", p);    
        */

        //Second try.
        int i = 0;
        while(i < strlen(str))
            {
              p[i] = str[i];
              i++;
            }
        p[i] = '\0';
        printf("%s\n", p);
        return 0;  
    }

Upvotes: 2

Views: 67

Answers (1)

CXJ
CXJ

Reputation: 4469

Both methods work to copy the string. The error in the first method is in printing the copied string out when the loop is complete:

printf("%s\n", p);

At this point, p is pointing to the last character inserted into the copy, the null character, not the beginning of the string. So the printf() correctly prints nothing.

Upvotes: 1

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