C Programming Question and Answers
41. | What are preprocessor directives? |
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42. | What is the use of auto keyword? |
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When a certain variable is declared with the keyword auto and initialized to a certain value, then within the scope of the variable. It is reinitialized upon being called repeatedly. The keyword auto is used extremely rate. A variable is set by default to auto. The declarations auto int number, and int number. |
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43. | What is the purpose of register keyword? |
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It is used to make the computation faster.
The register keyword tells the compiler to store the variable onto the CPU register if space on the register is available. However, this a very old technique. Today's processors are smart enough to assign the registers themselves and hence using the register keywords can actually slowdown the operations if the usage is incorrect. The keyword register instructs the compiler to persist the variable that is being declared in a CPU registers. |
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44. | What is the difference between null and zero? |
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