While working with character and strings we need to use predefined string type functions for making our task easy and efficient.

Strlen function is used to find the length of the string.

#include <stdio.h>
#include <string.h>
int main(){
    char a[20]="Program";
    char b[20]={'P','r','o','g','r','a','m','\0'};
    char c[20];
    printf("Enter string: ");
    gets(c);  
    printf("Length of string a=%d \n",strlen(a));
    //calculates the length of string before null charcter.
    printf("Length of string b=%d \n",strlen(b));   
    printf("Length of string c=%d \n",strlen(c));
    return 0;
}

Strcpy function is used to copy the string from source to destination

#include <stdio.h>
#include <string.h>
int main(){
    char a[10],b[10];
    printf("Enter string: ");
    gets(a);
    strcpy(b,a);   //Content of string a is copied to string b.
    printf("Copied string: ");
    puts(b);
    return 0;
}

Strcat function is used to concatenate string.

#include <stdio.h>
#include <string.h>
int main(){
    char str1[]="This is ", str2[]="demo program";
    strcat(str1,str2);   //concatenates str1 and str2 and resultant string is stored in str1.
    puts(str1);    
    puts(str2); 
    return 0;
}

getc() and putc()

For taking the input as character type and displaying it as an character type these functions are used

#include<stdio.h>
int main(){
    char name[30];
    printf("Enter name: ");
for(int i=0;i<=29;i++)
{
    getc(name[i]);     //Function to read string from user.
} 

for(int i=0;i<=29;i++)
{
   printf("Name: ");
    puts(name[i]);      //Function to display string.
}  
    return 0;
}

gets() and puts()

For taking entire string as input or displaying it without using an array you can use gets and puts for it.

#include<stdio.h>
int main(){
    char name[30];
    printf("Enter name: ");
    gets(name);     //Function to read string from user.
    printf("Name: ");
    puts(name);    //Function to display string.
    return 0;
}