C 언어에서 문자열을 이진 데이터로 변환하는 방법과 예제

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

void convertToASCII(const char *str) {
    for (int i = 0; i < strlen(str); i++) {
        printf("Character: %c, ASCII: %d\n", str[i], str[i]);
    }
}

int main() {
    const char *text = "Hello";
    printf("Original String: %s\n", text);
    printf("ASCII Conversion:\n");
    convertToASCII(text);
    return 0;
}

Original String: Hello  
ASCII Conversion:  
Character: H, ASCII: 72  
Character: e, ASCII: 101  
Character: l, ASCII: 108  
Character: l, ASCII: 108  
Character: o, ASCII: 111  

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

void saveToBinaryFile(const char *filename, const char *data) {
    FILE *file = fopen(filename, "wb");
    if (file == NULL) {
        perror("Error opening file");
        return;
    }

    size_t length = strlen(data);
    fwrite(data, sizeof(char), length, file);
    fclose(file);

    printf("Data successfully saved to binary file: %s\n", filename);
}

int main() {
    const char *text = "Hello, Binary World!";
    saveToBinaryFile("output.bin", text);
    return 0;
}

void readFromBinaryFile(const char *filename) {
    FILE *file = fopen(filename, "rb");
    if (file == NULL) {
        perror("Error opening file");
        return;
    }

    char buffer[256];
    size_t bytesRead = fread(buffer, sizeof(char), sizeof(buffer) - 1, file);
    buffer[bytesRead] = '\0';  // Null-terminate the string

    printf("Data read from binary file: %s\n", buffer);
    fclose(file);
}

int main() {
    readFromBinaryFile("output.bin");
    return 0;
}

[72, 101, 108, 108, 111]

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

void convertToByteArray(const char *str, unsigned char *byteArray, size_t *length) {
    size_t len = strlen(str);
    for (size_t i = 0; i < len; i++) {
        byteArray[i] = (unsigned char)str[i];
    }
    *length = len;
}

void printByteArray(const unsigned char *byteArray, size_t length) {
    printf("Byte Array: ");
    for (size_t i = 0; i < length; i++) {
        printf("%02X ", byteArray[i]);  // Print in hexadecimal format
    }
    printf("\n");
}

int main() {
    const char *text = "Hello";
    unsigned char byteArray[256];
    size_t length = 0;

    convertToByteArray(text, byteArray, &length);
    printf("Original String: %s\n", text);
    printByteArray(byteArray, length);

    return 0;
}

Original String: Hello  
Byte Array: 48 65 6C 6C 6F  

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/evp.h>  // OpenSSL 라이브러리 필요

// Base64 인코딩 함수
char *base64Encode(const char *input, size_t len, size_t *outLen) {
    char *encoded = (char *)malloc((4 * ((len + 2) / 3)) + 1);
    if (!encoded) return NULL;

    *outLen = EVP_EncodeBlock((unsigned char *)encoded, (unsigned char *)input, len);
    return encoded;
}

// Base64 디코딩 함수
char *base64Decode(const char *input, size_t len, size_t *outLen) {
    char *decoded = (char *)malloc((3 * (len / 4)) + 1);
    if (!decoded) return NULL;

    *outLen = EVP_DecodeBlock((unsigned char *)decoded, (unsigned char *)input, len);
    return decoded;
}

int main() {
    const char *text = "Hello, Encoding!";
    size_t encodedLen, decodedLen;

    // Base64 인코딩
    char *encoded = base64Encode(text, strlen(text), &encodedLen);
    printf("Original Text: %s\n", text);
    printf("Base64 Encoded: %s\n", encoded);

    // Base64 디코딩
    char *decoded = base64Decode(encoded, encodedLen, &decodedLen);
    decoded[decodedLen] = '\0';  // Null-terminate the decoded string
    printf("Base64 Decoded: %s\n", decoded);

    free(encoded);
    free(decoded);
    return 0;
}

Original Text: Hello, Encoding!  
Base64 Encoded: SGVsbG8sIEVuY29kaW5nIQ==  
Base64 Decoded: Hello, Encoding!  

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

// 구조체 정의
typedef struct {
    int id;
    char name[50];
    float score;
} Student;

// 구조체 데이터를 파일에 직렬화
void serialize(const char *filename, const Student *student) {
    FILE *file = fopen(filename, "wb");
    if (file == NULL) {
        perror("Error opening file");
        return;
    }
    fwrite(student, sizeof(Student), 1, file);
    fclose(file);
    printf("Data serialized to file: %s\n", filename);
}

// 파일에서 구조체 데이터를 역직렬화
void deserialize(const char *filename, Student *student) {
    FILE *file = fopen(filename, "rb");
    if (file == NULL) {
        perror("Error opening file");
        return;
    }
    fread(student, sizeof(Student), 1, file);
    fclose(file);
    printf("Data deserialized from file: %s\n", filename);
}

int main() {
    const char *filename = "student.dat";

    // 직렬화할 데이터 생성
    Student student1 = {1, "Alice", 95.5};
    serialize(filename, &student1);

    // 역직렬화하여 데이터 복원
    Student student2;
    deserialize(filename, &student2);
    printf("Deserialized Data: ID=%d, Name=%s, Score=%.2f\n", student2.id, student2.name, student2.score);

    return 0;
}

Data serialized to file: student.dat  
Data deserialized from file: student.dat  
Deserialized Data: ID=1, Name=Alice, Score=95.50