// Program A: STUDENTS (1D array) - input, display, search #include <stdio.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); int STUDENTS[N];

for (int i = 0; i < N; i++) {
    printf("Enter roll number for student %d: ", i+1);
    scanf("%d", &STUDENTS[i]);
}

printf("\nRoll numbers:\n");
for (int i = 0; i < N; i++) printf("%d ", STUDENTS[i]);
printf("\n");

int key, found = 0;
printf("\nEnter roll number to search: ");
scanf("%d", &key);
for (int i = 0; i < N; i++) {
    if (STUDENTS[i] == key) { found = 1; printf("Found at position %d (index %d)\n", i+1, i); break; }
}
if (!found) printf("Roll number %d not found.\n", key);
return 0;

}

// Program B: MARKS (1D array) - input, sort descending, display #include <stdio.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); int MARKS[N];

for (int i = 0; i < N; i++) {
    printf("Enter marks for student %d: ", i+1);
    scanf("%d", &MARKS[i]);
}

// simple selection sort descending
for (int i = 0; i < N-1; i++) {
    int mx = i;
    for (int j = i+1; j < N; j++)
        if (MARKS[j] > MARKS[mx]) mx = j;
    if (mx != i) { int t = MARKS[i]; MARKS[i] = MARKS[mx]; MARKS[mx] = t; }
}

printf("\nMarks sorted in descending order:\n");
for (int i = 0; i < N; i++) printf("%d ", MARKS[i]);
printf("\n");
return 0;

}

// Program C: STUDENTS_MARK (2 x N) - make from STUDENTS and MARKS, display #include <stdio.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); int STUDENTS[N], MARKS[N], STUDENTS_MARK[2][N];

printf("Enter roll numbers:\n");
for (int i = 0; i < N; i++) scanf("%d", &STUDENTS[i]);
printf("Enter marks:\n");
for (int i = 0; i < N; i++) scanf("%d", &MARKS[i]);

// assign into 2xN array
for (int j = 0; j < N; j++) {
    STUDENTS_MARK[0][j] = STUDENTS[j]; // row 0 = roll
    STUDENTS_MARK[1][j] = MARKS[j];    // row 1 = mark
}

printf("\nSTUDENTS_MARK (2 x %d):\n", N);
for (int i = 0; i < 2; i++) {
    for (int j = 0; j < N; j++) printf("%d\t", STUDENTS_MARK[i][j]);
    printf("\n");
}
return 0;

}

// Program D: STUDENTS_MARKS (4 x N) - row0:roll, row1..3:marks of 3 subjects #include <stdio.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); int STUDENTS_MARKS[4][N];

printf("Enter roll numbers (row 0):\n");
for (int j = 0; j < N; j++) scanf("%d", &STUDENTS_MARKS[0][j]);

for (int subj = 1; subj <= 3; subj++) {
    printf("Enter marks for subject %d:\n", subj);
    for (int j = 0; j < N; j++) scanf("%d", &STUDENTS_MARKS[subj][j]);
}

printf("\nSTUDENTS_MARKS (4 x %d):\n", N);
for (int i = 0; i < 4; i++) {
    for (int j = 0; j < N; j++) printf("%d\t", STUDENTS_MARKS[i][j]);
    printf("\n");
}
return 0;

}

// Program E: STUDENTS_NAMES - input and display string array of names #include <stdio.h> #include <string.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); char STUDENTS_NAMES[N][50];

for (int i = 0; i < N; i++) {
    printf("Enter name of student %d: ", i+1);
    scanf("%s", STUDENTS_NAMES[i]); // reads single token name
}

printf("\nStudent names:\n");
for (int i = 0; i < N; i++) printf("%s\n", STUDENTS_NAMES[i]);
return 0;

}

// Program F: STUDENTS_NAMES_SORTED - copy and sort names alphabetically (uses strcpy) #include <stdio.h> #include <string.h>

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); char STUDENTS_NAMES[N][50], STUDENTS_NAMES_SORTED[N][50], tmp[50];

for (int i = 0; i < N; i++) {
    printf("Enter name %d: ", i+1);
    scanf("%s", STUDENTS_NAMES[i]);
    strcpy(STUDENTS_NAMES_SORTED[i], STUDENTS_NAMES[i]); // copy
}

// sort copy
for (int i = 0; i < N-1; i++) {
    for (int j = i+1; j < N; j++) {
        if (strcmp(STUDENTS_NAMES_SORTED[i], STUDENTS_NAMES_SORTED[j]) > 0) {
            strcpy(tmp, STUDENTS_NAMES_SORTED[i]);
            strcpy(STUDENTS_NAMES_SORTED[i], STUDENTS_NAMES_SORTED[j]);
            strcpy(STUDENTS_NAMES_SORTED[j], tmp);
        }
    }
}

printf("\nOriginal names:\n");
for (int i = 0; i < N; i++) printf("%s\n", STUDENTS_NAMES[i]);

printf("\nSorted names (STUDENTS_NAMES_SORTED):\n");
for (int i = 0; i < N; i++) printf("%s\n", STUDENTS_NAMES_SORTED[i]);

return 0;

}

// Program G: Calculate_Average - computes average of 3 subject marks from STUDENTS_MARKS (4xN) #include <stdio.h>

void Calculate_Average(int STUDENTS_MARKS[4][100], int N, float AVERAGE[]) { for (int j = 0; j < N; j++) { int sum = 0; for (int i = 1; i <= 3; i++) sum += STUDENTS_MARKS[i][j]; AVERAGE[j] = sum / 3.0f; } }

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); int STUDENTS_MARKS[4][100]; float AVERAGE[N];

printf("Enter roll numbers (row 0):\n");
for (int j = 0; j < N; j++) scanf("%d", &STUDENTS_MARKS[0][j]);

for (int subj = 1; subj <= 3; subj++) {
    printf("Enter marks for subject %d:\n", subj);
    for (int j = 0; j < N; j++) scanf("%d", &STUDENTS_MARKS[subj][j]);
}

Calculate_Average(STUDENTS_MARKS, N, AVERAGE);

printf("\nAVERAGE of each student:\n");
for (int j = 0; j < N; j++)
    printf("Roll %d -> %.2f\n", STUDENTS_MARKS[0][j], AVERAGE[j]);

return 0;

}

// Program H: Find_Topper - find student with maximum average and print their name #include <stdio.h> #include <string.h>

void Find_Topper(float AVERAGE[], int N, char STUDENTS_NAMES[][50]) { int idx = 0; for (int i = 1; i < N; i++) if (AVERAGE[i] > AVERAGE[idx]) idx = i; printf("The topper is : %s (average = %.2f)\n", STUDENTS_NAMES[idx], AVERAGE[idx]); }

int main() { int N; printf("Enter number of students: "); scanf("%d", &N); float AVERAGE[N]; char STUDENTS_NAMES[N][50];

for (int i = 0; i < N; i++) {
    printf("Enter name of student %d: ", i+1);
    scanf("%s", STUDENTS_NAMES[i]);
    printf("Enter average marks of %s: ", STUDENTS_NAMES[i]);
    scanf("%f", &AVERAGE[i]);
}

Find_Topper(AVERAGE, N, STUDENTS_NAMES);
return 0;

}