Adding weather report.

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Author: Nibba2018

C/Weather-Details/.gitignore

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+key

C/Weather-Details/Makefile

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+geom: weather.c
+	gcc weather.c -lcurl -ljson-c -o weather
+	touch key
+
+cleanup:
+	rm weather

C/Weather-Details/README.md

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+# Get Weather Details of a city
+The following program uses cURL to perform an HTTP GET request to Open Weather API. The reponse(JSON) is then parsed with the help of json-c library to extract the necessary information. Makefile is responsible for automated compilation of the script. Terminal output is colored using ANSI codes for green and yellow.
+
+## Dependencies
+  * cURL
+  * json-c
+
+## Running script
+  * Build by running: `make`
+  * Save your API key in `key` file.
+  * Execute by : `./weather <city-name>`
+  * for e.g : `./weather Kolkata`
+
+## Output
+
+![output](output.png)

C/Weather-Details/output.png

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+#include<stdio.h>
+#include<curl/curl.h>
+#include<json-c/json.h>
+#include<string.h>
+
+// Callback function to handle API response.
+static size_t write_callback(char *contents, size_t size, size_t nmemb, void *userp)
+{
+    // Json objects to parse response.
+    json_object *parsed_json, *main_data, *temp, *wind, *wind_speed, *humidity;
+
+    // Tokenise JSON
+    parsed_json = json_tokener_parse(contents);
+
+    // Extract data from JSON response.
+    json_object_object_get_ex(parsed_json, "main", &main_data);
+    json_object_object_get_ex(main_data, "temp", &temp);
+    json_object_object_get_ex(main_data, "humidity", &humidity);
+    json_object_object_get_ex(parsed_json, "wind", &wind);
+    json_object_object_get_ex(wind, "speed", &wind_speed);
+
+    // Print json response with color.
+    printf("\033[93mTemperature: %s°C\033[0m\n", json_object_get_string(temp));
+    printf("\033[93mHumidity   : %s%%\033[0m\n", json_object_get_string(humidity));
+    printf("\033[93mWind Speed : %sknots\033[0m\n", json_object_get_string(wind_speed));
+
+    // return size of the data handled.
+    return size * nmemb;
+}
+
+
+int main(int argc, char **argv)
+{
+    // Define necessary variables.
+    char *location = argv[1];
+    char key[64], url[1024];
+
+    // Initialise CURL structures.
+    CURL *curl;
+    CURLcode res;
+
+    // Open key file to extract API key.
+    FILE *fp = fopen("key", "r");
+    if(fp == NULL)
+    {
+        fprintf(stderr, "Unable to open `key` file.");
+        exit(1);
+    }
+    fgets(key, 64, fp);
+    fclose(fp);
+
+    // Formulate the API endpoint.
+    sprintf(url, "https://api.openweathermap.org/data/2.5/weather?q=%s&units=metric&appid=%s", location, key);
+
+    printf("\033[92mWeather details for %s:\n", location);
+
+    // Perform a GET HTTP request.
+    curl = curl_easy_init();
+    if(curl)
+    {
+        // Set CURL options
+        curl_easy_setopt(curl, CURLOPT_URL, url);
+        curl_easy_setopt(curl, CURLOPT_WRITEFUNCTION, write_callback);
+
+        // Perform the request, res will get the return code
+        res = curl_easy_perform(curl);
+        /* Check for errors */
+        if(res != CURLE_OK)
+            fprintf(stderr, "curl_easy_perform() failed: %s\n", curl_easy_strerror(res));
+
+        // cleanup
+        curl_easy_cleanup(curl);
+    }
+
+    return 0;
+}