C언어 Level 7

1~5. 다음 코드에 대한 출력 결과를 쓰시오.

 

1.

#include <stdio.h>
int main() {
    FILE *fp = fopen("test.txt", "w");
    if (fp != NULL) {
        fprintf(fp, "Hello, File!\n");
        fclose(fp);
    }
    fp = fopen("test.txt", "r");
    char buffer[20];
    if (fp != NULL) {
        fscanf(fp, "%s", buffer);
        printf("%s\n", buffer);
        fclose(fp);
    }
    return 0;
}

 

2.

#include <stdio.h>
int main() {
    FILE *fp = fopen("data.bin", "wb");
    int num = 1234;
    fwrite(&num, sizeof(int), 1, fp);
    fclose(fp);
    fp = fopen("data.bin", "rb");
    int read_num;
    fread(&read_num, sizeof(int), 1, fp);
    printf("%d\n", read_num);
    fclose(fp);
    return 0;
}

 

3.

#include <stdio.h>
int main() {
    FILE *fp = fopen("output.txt", "w");
    if (fp != NULL) {
        for (int i = 0; i < 3; i++) {
            fprintf(fp, "Line %d\n", i + 1);
        }
        fclose(fp);
    }
    fp = fopen("output.txt", "r");
    char line[20];
    if (fp != NULL) {
        while (fgets(line, sizeof(line), fp) != NULL) {
            printf("%s", line);
        }
        fclose(fp);
    }
    return 0;
}

 

4.

#include <stdio.h>
int main() {
    FILE *fp = fopen("numbers.txt", "w");
    if (fp != NULL) {
        for (int i = 1; i <= 5; i++) {
            fprintf(fp, "%d ", i * 2);
        }
        fclose(fp);
    }
    fp = fopen("numbers.txt", "r");
    int num;
    while (fscanf(fp, "%d", &num) != EOF) {
        printf("%d ", num);
    }
    fclose(fp);
    return 0;
}

 

5.

#include <stdio.h>
int main() {
    FILE *fp = fopen("text.txt", "w");
    if (fp != NULL) {
        fputs("Hello, World!", fp);
        fclose(fp);
    }
    fp = fopen("text.txt", "r");
    char buffer[50];
    if (fp != NULL) {
        fgets(buffer, sizeof(buffer), fp);
        printf("%s\n", buffer);
        fclose(fp);
    }
    return 0;
}

 

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정답
(드래그 시 정답이 보입니다.)

1. Hello,
2. 1234
3. Line 1

Line 2

Line 3
4. 2 4 6 8 10
5. Hello, World!