codes for entertainment purpose

1.calculates and prints the number of and sum of the integers between 1 and 100 (inclusive) that are not divisible by 3 or 5

codes:

#include<stdio.h>
int main(){
    int i;
    int sum=0;
    int count=0;
    for(i=1;i<=100;i++){
        if(i%3!=0 && i%5!=0){
            sum=sum+i;
            count=count+1;
        }
    }
    printf("sum=%d number=%d\n",sum,count);
    return 0;
}

2.The program prompts for a string (max 80 characters) and converts uppercase characters to lowercase

codes:

#include <stdio.h>
#include <string.h>
 
int main(void) {
    char str[81];
    int i, len;
    printf("Enter string:\n");
    fgets(str, 81, stdin);
    len = strlen(str);
    if(str[len-1] == '\n') {
        str[len-1] = 0;
    }
    for(i=0; str[i]; i++) {
        if(str[i] >= 'A' && str[i] <= 'Z') {
            str[i] += 32;
        }
    }
    printf("%s\n", str);
    return 0;
}

3.Convert lowercase characters to uppercase instead.

codes:

#include <stdio.h>
#include <string.h>
 
int main(void) {
    char str[81];
    int i, len;
    printf("Enter string:\n");
    fgets(str, 81, stdin);
    len = strlen(str);
    if(str[len-1] == '\n') {
        str[len-1] = 0;
    }
    for(i=0; str[i]; i++) {
        if(str[i] >= 'a' && str[i] <= 'z') {
            str[i] -= 32;
        }
    }
    printf("%s\n", str);
    return 0;
}

4.Count the number of each type of letter (A to Z) and print a table showing these counts. Ignore non-alphabetic characters.

codes:

#include <stdio.h>
#include <string.h>
 
int main(void) {
	char str[81];
	int lettercount[26]; 
	int i, len;
 
	for(i=0; i<26; i++) {
		lettercount[i] = 0;
	}
 
	printf("Enter string:\n");
	fgets(str, 81, stdin);
 
	len = strlen(str);
 
	if(str[len-1] == '\n') {
		str[len-1] = 0; 
	}
 
	for(i=0; str[i]; i++) {
		if(str[i] >= 'A' && str[i] <= 'Z') {
			lettercount[str[i]-'A']++;
		} else if(str[i] >= 'a' && str[i] <= 'z') {
			lettercount[str[i]-'a']++;
		}
	}
 
	for(i=0; i<26; i++) {
		printf("%c: %d\n", 'A'+i, lettercount[i]);
	}
	return 0;
}

5.Accept 20 lines of text (each up to 80 characters) instead of 1 line, then print a count of each letter seen (the total over all lines).

codes:

#include <stdio.h>
#include <string.h>
 
int main(void) {
	char str[81];
	int lettercount[26]; 
	int i, len;
	int linecount;
 
	for(i=0; i<26; i++) {
		lettercount[i] = 0;
	}
 
	for(linecount=0; linecount<20; linecount++) {
	    printf("Enter string:\n");
	    fgets(str, 81, stdin);
 
	    len = strlen(str);
 
	    if(str[len-1] == '\n') {
		    str[len-1] = 0; /* Null character - we could also have said '\0' */
	    }
 
	    for(i=0; str[i]; i++) {
		    if(str[i] >= 'A' && str[i] <= 'Z') {
			    lettercount[str[i]-'A']++;
		    } else if(str[i] >= 'a' && str[i] <= 'z') {
			    lettercount[str[i]-'a']++;
		    }
	    }
	}
 
	for(i=0; i<26; i++) {
		printf("%c: %d\n", 'A'+i, lettercount[i]);
	}
	return 0;
}

6.As 5, but the program accepts any number of lines of text, up to when it sees a line containing only the text “END” (without the quotes)

codes:

#include <stdio.h>
#include <string.h>
 
int main(void) {
	char str[81];
	int lettercount[26]; 
	int i, len;
	int finished=0;	
	for(i=0; i<26; i++) {
		lettercount[i] = 0;
	}
 
	while(!finished) {
	   
	    printf("Enter string:\n");
	    fgets(str, 81, stdin);
 
	    
	    len = strlen(str);
 
	    
	    if(str[len-1] == '\n') {
		    str[len-1] = 0; 
	    }
 
	    
	    if(strcmp(str, "END") == 0) {
		    
		    break;
	    }
 
	 
	    for(i=0; str[i]; i++) {
		    if(str[i] >= 'A' && str[i] <= 'Z') {
			    lettercount[str[i]-'A']++;
		    } else if(str[i] >= 'a' && str[i] <= 'z') {
			    lettercount[str[i]-'a']++;
		    }
	    }
	}
 
	for(i=0; i<26; i++) {
		printf("%c: %d\n", 'A'+i, lettercount[i]);
	}
	return 0;
}