Arithmetic Operation On character

We can do arithmetic operation on character lets see some operation:

subtract a integer from a character:

 #include<stdio.h>  
 main()  
 {  
      char c='z';  //initialising
      char ch;  
      printf("\n c = %c",c);  
      ch=c-1;  //subtracting integer from charater
      printf("\n c-1=%c",ch);  
 }  

OUTPUT:- is nothing but character corressponding to ASCII volue=ASCII volue of 'z'-1

Using as comparison :

 #include<stdio.h>  
 #include<string.h>  
 main()  
 {  
      char str[50];  
      printf("\n enter string containing both capital & small character :\n::");  
      gets(str);  
      int len,i;  
      len=strlen(str);  
      printf("\n printing all character in capital letter\n:");  
      for(i=0;i<len;i++)  
      {  
           if(str[i]>='A' && str[i]<='Z') // use comparison to check letter is capital or not  
           {  
                printf("%c",str[i]);  
           }  
      }  
 }  

Here we compare character to find out whether input character is capital or small letter character.
so OUTPUT is :-

Find OUT Numerical VALue of a integer save as character:

 #include<stdio.h>  
 main()  
 {  
      char ch;  
      int n;  
      printf("\n input no between 0 to 9 which will be save as charcter :");  
      ch=getchar();  
      n=ch-'0';  
      printf("\n enter volue in ineger=%d",n);  
 }  

OUTPUT:

you can see clearly in above program is int x=char variable -'0'
then x=value of integer save as character variable.

TO convert string of integer into integer :

 A function defined in C name "atoi()" It convert integer string into real integer : Lets see an Example

 #include<stdio.h>  
 main()  
 {  
      char str[10];  
      printf("\n insert string of digit :");  
      gets(str);  
      int n;  
      n=atoi(str);// convert to integer  
      printf("interger save as string is : %d",n);  
 }  

OUTPut is :