GATE CS 2026 Set 1 Q17 — Lexical Analysis

To determine the correct option, let's analyze each statement phase-by-phase during compilation:

1. Statement S1:

   char *str1 = "Hello;    /* Statement S1 */

   • The string literal starts with a double quote " but is never closed on the same line.
   • In C, a string literal must be closed on the same line unless a backslash (\) is used for continuation.
   • Because the lexical analyzer (scanner) cannot group these characters into a valid string token, this results in an unclosed string literal error, which is a lexical error.
2. Statement S2:

   char *str2 = "Hello;";  /* Statement S2 */

   • This statement is perfectly valid. The string literal "Hello;" is correctly closed, and assigning it to a char * is type-compatible. There are no errors.
3. Statement S3:

   int *str3 = "Hello";    /* Statement S3 */

   • The tokens are lexically valid, and the statement is syntactically correct according to the grammar rules of variable declarations.
   • However, during semantic analysis, the compiler performs type checking. Here, a string literal of type char * is being assigned to a pointer of type int *.
   • This incompatible pointer assignment (type mismatch) is a semantic error.

Thus, S1 has a lexical error and S3 has a semantic error.