Write functions to implement string operations such as compare, concatenate, string length. Convince the parameter passing techniques Program and Algorithm Computer Science Engineering VTU

STRINGconcatenation

#include<stdio.h>
#include<stdlib.h>
int length (char str[]);
int compare (char str1[],char str2[]);
void concatenate (char str1[],char str2[]);
void main()
{
    char str1[30],str2[30];
    int choice,a,i,j;
    printf("enter 1-string comparision\n");
    printf("enter 2-string length\n");
    printf("enter 3-string concatenation\n");
    printf("enter 4-exit\n");
    scanf("%d",&choice);
    switch(choice)
    {
        case 1:printf("enter string 1\n");
        scanf("%s",str1);
        printf("enter string 2\n");
        scanf("%s",str2);
        a=compare(str1,str2);
        if(a==0)
        {
            printf("%s and%s are identical\n",str1,str2);
        }
        else
        {
            printf("%s and%s are not identical\n",str1,str2);
        }
        break;
        case 2:printf("enter a sring\n");
        scanf("%s",str1);
        a=length(str1);
        printf("length of %s=%d\n",str1,a);
        break;
        case 3: printf("enter string 1\n");
        scanf("%s",str1);
        printf("enter string 2\n");
        scanf ("%s",str2);
        concatenate (str1,str2);
        break;
        case 4:exit(0);
        break;
        default:printf("enter proper choice\n");
        exit(0);
    }
    }
        int length(char str[])
{
    int len=0;
    while(str[len]!='\0')
    len++;
    return len;
}
    int compare(char str1[],char str2[])
{
    int i=0;
    while (str1[i]==str2[i])
    {
        if(str1[i]=='\0' || str2[i]=='\0')
        break;
        i++;
    }
    return str1[i]-str2[i];
}
    void concatenate (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';
    printf("concatenated string is %s\n",str1);
    }

STRINGconcatenation

Start
Declare the required variables
Read choice 1 – String compare, 2 – String length, 3 – String concatenate, 4 - Exit
if choice is equal to 1
Read two strings as str1 and str2
c = compare(str1,str2)
if c ==  0 display identical strings
else display non identical strings
if choice is equal to 2
Read string as str
len = length(str)
Display len
if choice is equal to 3
Read two strings as str1 and str2
str = concatenate(str1,str2)
Display str      
Stop
Algorithm :  String compare
i = 0
while str1[i] == str2[i] do
if str1[i] == ‘\0’ or str2[i] == ‘\0’ break
i = i + 1
return str1[i] – str2[i]
Algorithm : String length
i = 0
while str [i] != ‘\0’ do
i = i + 1
return i
Algorithm : String concatenate
i = 0, j = 0
while str1[i] != ‘\0’ do
i = i + 1
while str2[i] != ‘\0’ do
str1[i] = str2[j]
i = i + 1
j = j + 1
str1[i] = ‘\0’
return str1