void print_usage(char *file)
时间: 2024-04-04 15:34:02 浏览: 12
这是一个自定义函数,用于打印程序的使用说明。该函数的参数为程序的文件名,用于在提示信息中显示当前程序的名称。
在这里,print_usage 函数用于打印当前程序的使用说明,其中包括程序的名称以及各个参数的使用方法和说明。该函数通常在用户输入错误的参数或者没有输入参数时被调用,用于提示用户正确的使用方法。
相关问题
#include <stdio.h> #include <iostream> #include <chrono> #include <thread> #include <DjiRtspImageSource.h> #define STB_IMAGE_WRITE_IMPLEMENTATION #include "stb_image_write.h" static inline int64_t now() { return std::chrono::duration_cast<std::chrono::milliseconds>(std::chrono::system_clock::now().time_since_epoch()).count(); } static int write_data_to_file(const char* name, uint8_t* data, int size) { FILE* fd = fopen(name, "wb"); if(fd) { int w = (int)fwrite(data, 1, size, fd); fclose(fd); return w; } else { return -1; } } char rtsp_url = "rtsp://192.168.42.142:8554/live"; int main(int argc, char** argv) { if(argc < 1) return -1; if(argc == 1) { std::cout << "Usage : " << argv[0] << " <url>" << std::endl; return -1; } int64_t ts = now(); DjiRtspImageSource service(rtsp_url); service.setImageCallback(nullptr, [&ts](void* handler, uint8_t* frmdata, int frmsize, int width, int height, int pixfmt) -> void { printf("Image %d@%p -- %dx%d -- %d\n", frmsize, frmdata, width, height, pixfmt); if(frmdata) { int64_t t = now(); if(t - ts > 1000) { ts = t; char name[64]; static int counter = 0; sprintf(name, "pictures/%dx%d-%d_%d.jpg", width, height, pixfmt, ++counter); if(pixfmt == 5) stbi_write_jpg(name, width, height, 3, frmdata, 80); } } }); service.start(); for(;;) //for(int i=0; i<30; i++) { std::this_thread::sleep_for(std::chrono::milliseconds(1000)); } service.stop(); std::cout << "done." << std::endl; return 0; } 上述c++代码帮我同等转换成python代码
你好!以下是将上述 C++ 代码转换为 Python 代码的等效版本:
```python
import cv2
import time
rtsp_url = "rtsp://192.168.42.142:8554/live"
def write_data_to_file(name, data):
with open(name, "wb") as fd:
fd.write(data)
return len(data)
return -1
def image_callback(handler, frmdata, frmsize, width, height, pixfmt):
print(f"Image {frmsize}@{frmdata} -- {width}x{height} -- {pixfmt}")
if frmdata:
t = int(time.time() * 1000)
if t - ts > 1000:
ts = t
name = f"pictures/{width}x{height}-{pixfmt}_{counter}.jpg"
if pixfmt == 5:
write_data_to_file(name, frmdata)
def main(rtsp_url):
ts = int(time.time() * 1000)
service = cv2.VideoCapture(rtsp_url)
counter = 0
while True:
ret, frame = service.read()
if not ret:
break
t = int(time.time() * 1000)
if t - ts > 1000:
ts = t
counter += 1
name = f"pictures/{frame.shape[1]}x{frame.shape[0]}-5_{counter}.jpg"
cv2.imwrite(name, frame, [int(cv2.IMWRITE_JPEG_QUALITY), 80])
service.release()
print("done.")
if __name__ == "__main__":
main(rtsp_url)
```
请注意,上述 Python 代码使用了 `cv2` 库来处理视频流和图像。确保在运行代码之前,已经安装了相应的库。此外,Python 代码中的图像保存路径 `pictures/` 需要事先存在。
写一个好用的linux文本io加密/解密代码
以下是一个较为完整的、好用的Linux文本IO加密/解密代码的示例,使用了openssl库中的AES算法:
```c
#include <openssl/aes.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define KEY_SIZE 256
#define BLOCK_SIZE 16
#define BUFFER_SIZE 1024
void print_error(const char *msg) {
printf("Error: %s\n", msg);
}
void print_usage(const char *prog_name) {
printf("Usage: %s <encrypt/decrypt> <input file> <output file> <key>\n", prog_name);
}
int encrypt_file(const char *in_filename, const char *out_filename, const char *key_str) {
unsigned char key[KEY_SIZE/8];
AES_KEY aes_key;
int bytes_read, bytes_written;
unsigned char in_data[BLOCK_SIZE];
unsigned char out_data[BLOCK_SIZE];
FILE *in_file = fopen(in_filename, "rb");
FILE *out_file = fopen(out_filename, "wb");
if (!in_file) {
print_error("Could not open input file for reading.");
return -1;
}
if (!out_file) {
print_error("Could not open output file for writing.");
fclose(in_file);
return -1;
}
// Convert key string to binary
memset(key, 0, sizeof(key));
memcpy(key, key_str, strlen(key_str));
// Set encryption key
AES_set_encrypt_key(key, KEY_SIZE, &aes_key);
// Encrypt file
while ((bytes_read = fread(in_data, 1, BLOCK_SIZE, in_file)) > 0) {
AES_encrypt(in_data, out_data, &aes_key);
bytes_written = fwrite(out_data, 1, bytes_read, out_file);
if (bytes_written != bytes_read) {
print_error("Error writing encrypted data.");
fclose(in_file);
fclose(out_file);
return -1;
}
}
fclose(in_file);
fclose(out_file);
return 0;
}
int decrypt_file(const char *in_filename, const char *out_filename, const char *key_str) {
unsigned char key[KEY_SIZE/8];
AES_KEY aes_key;
int bytes_read, bytes_written;
unsigned char in_data[BLOCK_SIZE];
unsigned char out_data[BLOCK_SIZE];
FILE *in_file = fopen(in_filename, "rb");
FILE *out_file = fopen(out_filename, "wb");
if (!in_file) {
print_error("Could not open input file for reading.");
return -1;
}
if (!out_file) {
print_error("Could not open output file for writing.");
fclose(in_file);
return -1;
}
// Convert key string to binary
memset(key, 0, sizeof(key));
memcpy(key, key_str, strlen(key_str));
// Set decryption key
AES_set_decrypt_key(key, KEY_SIZE, &aes_key);
// Decrypt file
while ((bytes_read = fread(in_data, 1, BLOCK_SIZE, in_file)) > 0) {
AES_decrypt(in_data, out_data, &aes_key);
bytes_written = fwrite(out_data, 1, bytes_read, out_file);
if (bytes_written != bytes_read) {
print_error("Error writing decrypted data.");
fclose(in_file);
fclose(out_file);
return -1;
}
}
fclose(in_file);
fclose(out_file);
return 0;
}
int encrypt_decrypt_file(const char *mode, const char *in_filename, const char *out_filename, const char *key_str) {
if (strcmp(mode, "encrypt") == 0) {
return encrypt_file(in_filename, out_filename, key_str);
} else if (strcmp(mode, "decrypt") == 0) {
return decrypt_file(in_filename, out_filename, key_str);
} else {
print_error("Invalid mode. Must be 'encrypt' or 'decrypt'.");
return -1;
}
}
int main(int argc, char *argv[]) {
if (argc != 5) {
print_usage(argv[0]);
return EXIT_FAILURE;
}
const char *mode = argv[1];
const char *in_filename = argv[2];
const char *out_filename = argv[3];
const char *key_str = argv[4];
int ret = encrypt_decrypt_file(mode, in_filename, "tmp.txt", key_str);
if (ret != 0) {
return EXIT_FAILURE;
}
// Rename temporary file to output file
ret = rename("tmp.txt", out_filename);
if (ret != 0) {
print_error("Could not rename temporary file.");
remove("tmp.txt");
return EXIT_FAILURE;
}
printf("File %s %sed successfully.\n", in_filename, mode);
return EXIT_SUCCESS;
}
```
这个例子中,我们使用了256位的AES算法,并将加密和解密操作封装到`encrypt_file`和`decrypt_file`函数中。我们还实现了一个`encrypt_decrypt_file`函数来根据传递的模式(加密或解密)选择相应的函数来处理文件。我们还实现了一个完整的命令行接口,可以通过传递加密/解密模式、输入文件、输出文件和密钥来使用这些函数加密和解密文件。在加密和解密过程中,我们还加入了错误处理和文件IO操作的检查,使得代码更加健壮和可靠。