How to find the Index of Substring in C - Step by Step Examples

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How to find the Index of Substring in C ?

Answer

To find the index of a substring in C, you can use the strstr function.

✐ Examples

1 Find Index of Substring in String

In this example,

We include the string.h header file.
We create a string variable named str with a string value.
We use the strstr function to find the index of a specific substring within str.
The strstr function returns a pointer to the first occurrence of the substring in the string, which we can use to calculate the index.
Finally, we print the index.

C Program

#include <stdio.h>
#include <string.h>
int main() {
  char str[] = "Hello World";
  char* substr = strstr(str, "World");
  int index = substr - str;
  printf("Index of substring is: %d\n", index);
  return 0;
}

Output

Index of substring is: 6

2 Find Index of Substring in Another String

In this example,

We include the string.h header file.
We create two string variables named str1 and str2 with different values.
We use the strstr function to find the index of str2 within str1.
The strstr function returns a pointer to the first occurrence of str2 in str1, which we can use to calculate the index.
Finally, we print the index.

C Program

#include <stdio.h>
#include <string.h>
int main() {
  char str1[] = "apple banana cherry banana";
  char str2[] = "cherry";
  char* substr = strstr(str1, str2);
  int index = substr - str1;
  printf("Index of substring is: %d\n", index);
  return 0;
}

Output

Index of substring is: 13

Summary

In this tutorial, we learned How to find the Index of Substring in C language with well detailed examples.

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How to find the Index of Substring in C - Step by Step Examples

How to find the Index of Substring in C ?

Answer

✐ Examples

1 Find Index of Substring in String

C Program

Output

2 Find Index of Substring in Another String

C Program

Output

Summary

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