Question:C program to reverse a string using pointers 

#include<stdio.h>
int main(){
    char str[50];
    char rev[50];
    char *sptr = str;
    char *rptr = rev;
    int i=-1;

    printf("Enter any string : ");
    scanf("%s",str);
   
    while(*sptr){
     sptr++;
     i++;
    }

    while(i>=0){
     sptr--;
     *rptr = *sptr;
     rptr++;
     --i;
    }

    *rptr='\0';
  
    printf("Reverse of string is : %s",rev);
  
    return 0;
}
Sample output:
Enter any string : Pointer
Reverse of string is : retnioP

Question:C code to reverse a string by recursion 

#include<stdio.h>
#define MAX 100
char* getReverse(char[]);

int main(){

    char str[MAX],*rev;

    printf("Enter  any string: ");
    scanf("%s",str);

    rev = getReverse(str);

    printf("Reversed string is: %s",rev);
    return 0;
}

char* getReverse(char str[]){

    static int i=0;
    static char rev[MAX];

    if(*str){
         getReverse(str+1);
         rev[i++] = *str;
    }

    return rev;
}
Sample output:
Enter any string: mona
Reversed string is: anom

Question:String concatenation in c without using string functions 

#include<stdio.h>

void stringConcat(char[],char[]);
int main(){

    char str1[100],str2[100];
    int compare;

    printf("Enter first string: ");
    scanf("%s",str1);

    printf("Enter second string: ");
    scanf("%s",str2);

    stringConcat(str1,str2);

    printf("String after concatenation: %s",str1);

    return 0;
}

void stringConcat(char str1[],char str2[]){
    int i=0,j=0;
   
   
    while(str1[i]!='\0'){
         i++;
    }

    while(str2[j]!='\0'){
         str1[i] = str2[j];   
         i++;
         j++;
    }

    str1[i] = '\0';
}
Sample output:
Enter first string: cquestionbank
Enter second string: @blogspot.com
String after concatenation: cquestionbank@blogspot.com

Question:C program to compare two strings without using string functions 

#include<stdio.h>

int stringCompare(char[],char[]);
int main(){

    char str1[100],str2[100];
    int compare;

    printf("Enter first string: ");
    scanf("%s",str1);

    printf("Enter second string: ");
    scanf("%s",str2);

    compare = stringCompare(str1,str2);

    if(compare == 1)
         printf("Both strings are equal.");
    else
         printf("Both strings are not equal");
 
    return 0;
}

int stringCompare(char str1[],char str2[]){
    int i=0,flag=0;
   
    while(str1[i]!='\0' && str2[i]!='\0'){
         if(str1[i]!=str2[i]){
             flag=1;
             break;
         }
         i++;
    }

    if (flag==0 && str1[i]=='\0' && str2[i]=='\0')
         return 1;
    else
         return 0;

}
Sample output:
Enter first string: cquestionbank.blogspot.com
Enter second string: cquestionbank.blogspot.com
Both strings are equal.

Question:String copy without using strcpy in c programming language 

#include<stdio.h>

void stringCopy(char[],char[]);

int main(){

    char str1[100],str2[100];

    printf("Enter any string: ");
    scanf("%s",str1);

    stringCopy(str1,str2);

    printf("After copying: %s",str2);
 
    return 0;
}

void stringCopy(char str1[],char str2[]){
    int i=0;

    while(str1[i]!='\0'){
         str2[i] = str1[i];
         i++;
    }

    str2[i]='\0';
}
Sample output:
Enter any string: cquestionbank.blogspot.com
After copying: cquestionbank.blogspot.com

Question:Program to convert string into ASCII values in c programming language 

#include<stdio.h>

int main(){
  
    char str[100];
    int i=0;

    printf("Enter any string: ");
    scanf("%s",str);

    printf("ASCII values of each characters of given string: ");
    while(str[i])
         printf("%d ",str[i++]);
        
   
    return 0;
}
Sample Output:
Enter any string: cquestionbank.blogspot.com
ASCII values of each characters of given string: 99 113 117 101 115 116 105 111 110 98 97 110 107 46 98 108 111 103 115 112 111 116 46 99 111 109