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C program to check if a given string is Keyword or not

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  • Difficulty Level : Basic
  • Last Updated : 06 Feb, 2019
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Given a string, the task is to write a program that checks if the given string is a keyword or not.

  • Keywords are reserved words which cannot be used as variable names.
  • There are 32 keywords in C programming language.


Input: str = "geeks"
Output: geeks is not a keyword

Input: str = "for"
Output: for is a keyword

// C program to check whether a given
// string is a keyword or not
#include <stdbool.h>
#include <stdio.h>
#include <string.h>
// Function to check whether the given
// string is a keyword or not
// Returns 'true' if the string is a KEYWORD.
bool isKeyword(char* str)
    if (!strcmp(str, "auto") || !strcmp(str, "default"
        || !strcmp(str, "signed") || !strcmp(str, "enum"
        ||!strcmp(str, "extern") || !strcmp(str, "for"
        || !strcmp(str, "register") || !strcmp(str, "if"
        || !strcmp(str, "else")  || !strcmp(str, "int")
        || !strcmp(str, "while") || !strcmp(str, "do")
        || !strcmp(str, "break") || !strcmp(str, "continue"
        || !strcmp(str, "double") || !strcmp(str, "float")
        || !strcmp(str, "return") || !strcmp(str, "char")
        || !strcmp(str, "case") || !strcmp(str, "const")
        || !strcmp(str, "sizeof") || !strcmp(str, "long")
        || !strcmp(str, "short") || !strcmp(str, "typedef")
        || !strcmp(str, "switch") || !strcmp(str, "unsigned")
        || !strcmp(str, "void") || !strcmp(str, "static")
        || !strcmp(str, "struct") || !strcmp(str, "goto")
        || !strcmp(str, "union") || !strcmp(str, "volatile"))
        return (true);
    return (false);
// Driver code
int main()
    isKeyword("geeks") ? printf("Yes\n")
                       : printf("No\n");
    isKeyword("for") ? printf("Yes\n")
                     : printf("No\n");
    return 0;



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