This instructional material provides a detailed explanation of conditional control in the C language. Specifically designed for the Introductory Programming course at the Glasgow College of Electronic Science and Technology, these slides cover essential knowledge from getting started to mastering C language. In comparison to other online learning resources, these materials are more closely aligned with the actual college curriculum, offering greater specificity to help students establish a solid foundation for tackling more advanced professional courses. Upon completion of this course, you will gain valuable knowledge and the ability to write complex C language programs. The all-English slides also contribute to students' understanding of relevant English vocabulary, facilitating their integration into the international academic environment. Welcome to all first-year students at the Glasgow College of Electronic Science and Technology to explore, learn, and love C language through these materials!