Data read by libcurl functions can be saved to an open file or stored in memory, depending on how various options are set. When configured to save information to a file, the file is written using whatever data is read from the web. When configured to save information to memory, a special function is used to monitor the bytes read and increase the buffer size as new data arrives.
- Unless you direct it to do otherwise, … text generated by the libcurl function … curl_easy_perform is sent to standard output. … You can, however, save the text to a file … or redirect it to a buffer … providing you set the proper libcurl options. … So this code fetches information from a webpage … and saves it to a file. … The file is opened at line 14 … by using standard C library functions. … The libcurl easy interface is initialized … at line 22, … followed by various options. … At line 26, … the URL is specified. … At line 32, … the WRITEFUNCTION is set to the NULL pointer, … which directs libcurl to look for a file handle, … which is set at line 35. … So the output it sent to the open file … and not to standard output. … The file opened is closed at line 48. … And line 50 outputs a message to the user, … otherwise the program runs successfully … and would generate no output. … Now, I've already compiled the program. … So, we'll run it to see what it does. … It fetches the data, …
Author
Dan Gookin
Released
10/1/2019- Finding, installing, and linking libraries
- Accessing and generating XML data
- Working with JSON
- Working with the libcurl library
- Text programming
- Reading, writing, and manipulating JPEG images
- Working with PNG images
Skill Level Advanced
Duration
Views
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Introduction
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Using the exercise files1m 2s
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Working with the code2m 45s
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1. Setup and Configuration
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Understanding libraries2m 50s
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Finding a C library2m 44s
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Installing a library4m 15s
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Liking a library: IDE4m 10s
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2. Data Structures
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Understanding XML2m 23s
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Accessing XML data3m 26s
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Generating XML data3m 57s
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Working with JSON2m 39s
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Accessing JSON data3m 10s
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Reading JSON data3m 46s
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Creating JSON output3m 35s
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3. Web Access
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Testing libcurl2m 3s
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Fetching a web page3m 47s
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Saving web data3m 31s
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Sending data2m 35s
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4. Text Programming
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Working with wide characters3m 19s
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Building an ncurses program2m 27s
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Controlling the text screen2m 32s
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Making color text2m 56s
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Exploring ncurses input4m 6s
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5. Computer Graphics
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Accessing a JPEG2m 31s
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Manipulating JPEG images3m 5s
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Working with PNG images3m 57s
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Modifying a PNG image2m 26s
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Conclusion
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Writing your own library4m 19s
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Next steps1m 17s
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Video: Saving web data