strdup() In C

Purpose of strdup()

strdup() is one of the inbuilt string function in c programming which is used to duplicate a given string.

How strdup() works

The following diagram clearly illustrate the working principle of strdup() inbuilt string function in C.

In the above diagram strdup() takes single parameter say a str whose duplicate string will be generated by strdup() and assigned to another character variable say a dupstr.

Syntax - strdup() in C

• strdup() accepts single parameter.
• A parameter must be a string.
• To use strdup() inbuilt string function in C, we need to declare #include<string.h> header file.

strdup(str);

C Program - strdup()

Let us work through strdup() function. In the following program we will create a duplicate string using strdup() inbuilt string function.

#include <stdio.h>
#include<string.h>
int main()
{
char str1[30] = "this is strdup", *str2;
str2 = strdup(str1);
printf("The Original string is : %s ", str1);
printf("\nThe duplicated string is : %s ", str2);
return 0;
}

The Original string is : this is strdup
The duplicated string is : this is strdup

C Program - Without strdup()

Let us duplicate a string without using inbuilt string function strdup().

#include <stdio.h>
#include<string.h>
int main()
{
char str1[30] = "this is strdup", *str2;
char i;
str2 = str1;
printf("The Original string is : %s ", str1);
printf("\nThe duplicated string is :");
for(i=0;str1[i]!='\0';i++)
{
printf("%c", *str2++);
}
return 0;
}

The Original string is : this is strdup
The duplicated string is : this is strdup

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