DS_String(SAJID)

#include <stdio.h>
#include <string.h>

void subString(char str[], int len, int indx)
{
    int i;
    char temp[1001];
    int j = 0;
    int sz = strlen(str);
    if(indx > sz) {
        printf("Invalid input!\n");
        return 0;
    }
    for(i=indx; i<=indx+len; i++){
        temp[j++] = str[i];
        if(i==sz) break;
    }
    temp[j] = '\0';
    printf("%s\n", temp);
}

int findSubString(char str[], char substr[])
{
    int szS = strlen(str);
    int szSb = strlen(substr);
    int i=0, j=0;
    int index = -1;
    int cnt = 0;
    for( ; i<szS; ) {
        cnt = 0;
        j = 0;
        if(str[i]==substr[j]) {
            j = 0;
            while(str[i]==substr[j] && i<szS) {
                i++;
                j++;
                cnt++;
            }
            if(cnt==szSb) {
                index = i-szSb;
                break;
            }
        }
        else i++;
    }
    return index;
}
void insert(char str[], char newStr[], int indx)
{
    int szS = strlen(str);
    int szN = strlen(newStr);
    char temp[szS+szN+5];
    int i = 0;
    for(i = 0; i < indx; i++) {
        temp[i] = str[i];
    }
    int j = 0;
    for(i=indx; i<indx+szN; i++) {
        temp[i] = newStr[j++];
    }
    j = indx;
    for(i=indx+szN; i<szS+szN; i++) {
        temp[i] = str[j++];
    }
    temp[i] = '\0';
    printf("%s\n", temp);
}

void deleteStr(char str[], int len, int indx)
{
    char temp[1001];
    int i;
    int sz = strlen(str);
    for(i=0; i<indx; i++) {
        temp[i] = str[i];
    }
    int j = i;
    for(i=indx+len; i<sz; i++) {
        temp[j++] = str[i];
    }
    temp[j] = '\0';
    printf("%s\n", temp);
}

void replace(char str[], char strTR[], char strR[])
{
    char temp[2002];
    int indx = findSubString(str, strR);
    if(indx==-1) {
        printf("String to be replace is not found!\n");
        return;
    }
    int len = strlen(str);
    int lenR = strlen(strR);
    int lenTR = strlen(strTR);
    int i=0;
    for(i=0; i<indx; i++) {
        temp[i] = str[i];
    }
    int j=i;
    for(i=0; i<lenTR; i++) {
        temp[j++] = strTR[i];
    }
    for(i=indx+lenR; i<len; i++) {
        temp[j++] = str[i];
    }
    temp[j] = '\0';
    printf("%s", temp);
}

int main()
{
    char str[1001];
    int len = 0, indx = 0;

    //Assignment-1

    printf("\tAssignment-1:\n\n");

    printf("Enter a string(within 1000 characters): ");
    gets(str);
    printf("Enter the index(index staring from 0): ");
    scanf("%d", &indx);
    printf("Enter the length of the sub-string: ");
    scanf("%d", &len);

    subString(str, len, indx);

    // Assignment-2
    getchar();
    printf("\n\tAssignment-2:\n");

    printf("Enter the sub-string you are looking for: ");
    char substr[1001];
    gets(substr);
    int x = findSubString(str, substr);
    if(x==-1) printf("Sub-string not found\n");
    else printf("Sub-string found at index %d", x);

    // Assignment-3
    printf("\n\tAssignment-3:\n");

    char stringToInsert[1001];
    printf("Enter the string you want to insert: ");
    gets(stringToInsert);
    printf("Enter the index you want to insert the new string: ");
    scanf("%d", &indx);
    insert(str, stringToInsert, indx);

    // Assignment-4
    printf("\n\tAssignment-4:\n");
    printf("Enter the index from which you want to delete: ");
    scanf("%d", &indx);
    printf("Enter the size of sub-string you want to delete: ");
    scanf("%d", &len);
    deleteStr(str, len, indx);

    // Assignment-5
    printf("\n\tAssignment-5:\n");
    getchar();
    char strR[1001], strTR[1001];
    printf("Enter the sub-string you want to replace with: ");
    gets(strTR);
    printf("Enter the string you want to replace: ");
    gets(strR);
    replace(str, strTR, strR);
    return 0;
}